logic gates in computer

A logic gate is an elementary building block of a digital circuit. Most logic gates have two inputs and one output. At any given moment, every terminal is in one of the two binary conditions low(0) or high (1), represented by different voltage levels. The logic state of a terminal can, and generally does, change often, as the circuit processes data. In most logic gates, the low state is approximately zero volts (0 V), while the high state is approximately five volts positive (+5 V).

There are seven basic logic gates: AND, OR, XOR, NOT, NAND, NOR, and XNOR.

The AND gate is so named because, if 0 is called “false” and 1 is called “true,” the gate acts in the same way as the logical “and” operator. The following illustration and table show the circuit symbol and logic combinations for an AND gate. (In the symbol, the input terminals are at left and the output terminal is at right.) The output is “true” when both inputs are “true.” Otherwise, the output is “false.”

/WhatIs/images/and.gif (220 bytes)

AND gate

Input 1 Input 2 Output
     
  1  
1    
1 1 1

The OR gate gets its name from the fact that it behaves after the fashion of the logical inclusive “or.” The output is “true” if either or both of the inputs are “true.” If both inputs are “false,” then the output is “false.”

/WhatIs/images/or.gif (224 bytes)

OR gate

Input 1 Input 2 Output
     
  1 1
1   1
1 1 1

 

The XOR ( exclusive-OR ) gateacts in the same way as the logical “either/or.” The output is “true” if either, but not both, of the inputs are “true.” The output is “false” if both inputs are “false” or if both inputs are “true.” Another way of looking at this circuit is to observe that the output is 1 if the inputs are different, but 0 if the inputs are the same.

 

XOR gate

Input 1 Input 2 Output
     
  1 1
1   1
1 1  

 

A logical inverter , sometimes called a NOT gate to differentiate it from other types of electronic inverter devices, has only one input. It reverses the logic state.

 

/WhatIs/images/not.gif (240 bytes)

 

Inverter or NOT gate

Input Output
1  
  1

 

The NAND gate operates as an AND gate followed by a NOT gate. It acts in the manner of the logical operation “and” followed by negation. The output is “false” if both inputs are “true.” Otherwise, the output is “true.”

/WhatIs/images/nand.gif (240 bytes)

NAND gate

Input 1 Input 2 Output
    1
  1 1
1   1
1 1  

 

The NOR gate is a combination OR gate followed by an inverter. Its output is “true” if both inputs are “false.” Otherwise, the output is “false.”

/WhatIs/images/nor.gif (237 bytes)

NOR gate

Input 1 Input 2 Output
    1
  1  
1    
1 1  

 

The XNOR (exclusive-NOR) gateis a combination XOR gate followed by an inverter. Its output is “true” if the inputs are the same, and”false” if the inputs are different.

/WhatIs/images/xnor.gif (278 bytes)

XNOR gate

Input 1 Input 2 Output
    1
  1  
1    
1 1 1

Using combinations of logic gates, complex operations can be performed. In theory, there is no limit to the number of gates that can be arrayed together in a single device. But in practice, there is a limit to the number of gates that can be packed into a given physical space. Arrays of logic gates are found in digital integrated circuits (ICs). As IC technology advances, the required physical volume for each individual logic gate decreases and digital devices of the same or smaller size become capable of performing ever-more-complicated operations at ever-increasing speeds.

Advertisements

Computer memory

Computer memory is any physical device capable of storing information temporarily or permanently. For example, Random Access Memory (RAM), is a volatile memory that stores information on an integrated circuit used by the operating system,software, and hardware.

What does computer memory look like?

Below is an example picture of a 512 MB DIMM computer memory module. This memory module connects to thememory slot on a computermotherboard.

Computer memory

Volatile vs. non-volatile memory

Memory can be either volatile and non-volatile memory. Volatile memory is a memory that loses its contents when the computer or hardware device loses power. Computer RAM is an example of a volatile memory and is why if your computer freezes or reboots when working on a program, you lose anything that hasn’t been saved. Non-volatile memory, sometimes abbreviated as NVRAM, is a memory that keeps its contents even if the power is lost.EPROM is an example of a non-volatile memory.

What happens to memory when the computer is turned off?

As mentioned above because memory (RAM) is a volatile memory when the computer loses power anything stored in RAM is lost. For example, as you are working on creating a document it is stored in RAM if it is not saved to a non-volatile memory (e.g. the hard drive) it would be lost if the computer lost power.

Memory is not disk storage

storageIt is very common for new computer users to be confused by what parts in the computer are memory. Although both the hard drive and RAM are memory, it is more appropriate to refer to RAM as “memory” or “primary memory” and a hard drive as “storage” or “secondary storage.”

When someone asks how much memory is in your computer, it is often between 1GB and 16 GB of Random Access Memory (RAM) and several hundred gigabytes of even a terabyte of hard disk drive storage. In other words, you always have more hard drive space than RAM.

How is memory used

When a program such as your Internetbrowser is open, it is loaded from your hard drive and placed into RAM, which allows that program to communicate with the processor at higher speeds. Anything you save to your computer, such as a picture or video, is sent to your hard drive for storage.

Why is memory important or needed for a computer?

All of devices on a computer do not operate at the same speed and computer memory gives your computer a place to quickly access data. If the CPU had to wait for a secondary storage device like a hard disk drive the computer would be much slower.

Types of RAM

Some of the more common types of memory chips for computers are listed below.

These types of memory all fall into the general categories of SIMM or DIMM.

html lists

HTML offers web authors three ways for specifying lists of information. All lists must contain one or more list elements. Lists may contain:

  • <ul> – An unordered list. This will list items using plain bullets.
  • <ol> – An ordered list. This will use different schemes of numbers to list your items.
  • <dl> – A definition list. This arranges your items in the same way as they are arranged in a dictionary.

HTML Unordered Lists

An unordered list is a collection of related items that have no special order or sequence. This list is created by using HTML <ul> tag. Each item in the list is marked with a bullet.

Example

<!DOCTYPE html>
<html>
<head>
<title>HTML Unordered List</title>
</head>
<body>
<ul>
<li>Beetroot</li>
<li>Ginger</li>
<li>Potato</li>
<li>Radish</li>
</ul>
</body>
</html>

This will produce following result:

  • Beetroot
  • Ginger
  • Potato
  • Radish

The type Attribute

You can use type attribute for <ul> tag to specify the type of bullet you like. By default it is a disc. Following are the possible options:

<ul type="square">
<ul type="disc">
<ul type="circle">

Example

Following is an example where we used <ul type=”square”>

<!DOCTYPE html>
<html>
<head>
<title>HTML Unordered List</title>
</head>
<body>
   <ul type="square">
   <li>Beetroot</li>
   <li>Ginger</li>
   <li>Potato</li>
   <li>Radish</li>
   </ul>
</body>
</html>

This will produce following result:

  • Beetroot
  • Ginger
  • Potato
  • Radish

Example

Following is an example where we used <ul type=”disc”> :

<!DOCTYPE html>
<html>
<head>
<title>HTML Unordered List</title>
</head>
<body>
   <ul type="disc">
   <li>Beetroot</li>
   <li>Ginger</li>
   <li>Potato</li>
   <li>Radish</li>
   </ul>
</body>
</html>

This will produce following result:

  • Beetroot
  • Ginger
  • Potato
  • Radish

Example

Following is an example where we used <ul type=”circle”> :

<!DOCTYPE html>
<html>
<head>
<title>HTML Unordered List</title>
</head>
<body>
   <ul type="circle">
   <li>Beetroot</li>
   <li>Ginger</li>
   <li>Potato</li>
   <li>Radish</li>
   </ul>
</body>
</html>

This will produce following result:

  • Beetroot
  • Ginger
  • Potato
  • Radish

HTML Ordered Lists

If you are required to put your items in a numbered list instead of bulleted then HTML ordered list will be used. This list is created by using <ol> tag. The numbering starts at one and is incremented by one for each successive ordered list element tagged with <li>.

Example

<!DOCTYPE html>
<html>
<head>
<title>HTML Ordered List</title>
</head>
<body>
<ol>
<li>Beetroot</li>
<li>Ginger</li>
<li>Potato</li>
<li>Radish</li>
</ol>
</body>
</html>

This will produce following result:

  1. Beetroot
  2. Ginger
  3. Potato
  4. Radish

The type Attribute

You can use type attribute for <ol> tag to specify the type of numbering you like. By default it is a number. Following are the possible options:

<ol type="1"> - Default-Case Numerals.
<ol type="I"> - Upper-Case Numerals.
<ol type="i"> - Lower-Case Numerals.
<ol type="a"> - Lower-Case Letters.
<ol type="A"> - Upper-Case Letters.

Example

Following is an example where we used <ol type=”1″>

<!DOCTYPE html>
<html>
<head>
<title>HTML Ordered List</title>
</head>
<body>
   <ol type="1">
   <li>Beetroot</li>
   <li>Ginger</li>
   <li>Potato</li>
   <li>Radish</li>
   </ol>
</body>
</html>

This will produce following result:

  1. Beetroot
  2. Ginger
  3. Potato
  4. Radish

Example

Following is an example where we used <ol type=”I”>

<!DOCTYPE html>
<html>
<head>
<title>HTML Ordered List</title>
</head>
<body>
   <ol type="I">
   <li>Beetroot</li>
   <li>Ginger</li>
   <li>Potato</li>
   <li>Radish</li>
   </ol>
</body>
</html>

This will produce following result:

  1. Beetroot
  2. Ginger
  3. Potato
  4. Radish

Example

Following is an example where we used <ol type=”i”>

<!DOCTYPE html>
<html>
<head>
<title>HTML Ordered List</title>
</head>
<body>
   <ol type="i">
   <li>Beetroot</li>
   <li>Ginger</li>
   <li>Potato</li>
   <li>Radish</li>
   </ol>
</body>
</html>

This will produce following result:

  1. Beetroot
  2. Ginger
  3. Potato
  4. Radish

Example

Following is an example where we used <ol type=”A”>

<!DOCTYPE html>
<html>
<head>
<title>HTML Ordered List</title>
</head>
<body>
   <ol type="A">
   <li>Beetroot</li>
   <li>Ginger</li>
   <li>Potato</li>
   <li>Radish</li>
   </ol>
</body>
</html>

This will produce following result:

  1. Beetroot
  2. Ginger
  3. Potato
  4. Radish

Example

Following is an example where we used <ol type=”a”>

<!DOCTYPE html>
<html>
<head>
<title>HTML Ordered List</title>
</head>
<body>
   <ol type="a">
   <li>Beetroot</li>
   <li>Ginger</li>
   <li>Potato</li>
   <li>Radish</li>
   </ol>
</body>
</html>

This will produce following result:

  1. Beetroot
  2. Ginger
  3. Potato
  4. Radish

The start Attribute

You can use start attribute for <ol> tag to specify the starting point of numbering you need. Following are the possible options:

<ol type="1" start="4">    - Numerals starts with 4.
<ol type="I" start="4">    - Numerals starts with IV.
<ol type="i" start="4">    - Numerals starts with iv.
<ol type="a" start="4">    - Letters starts with d.
<ol type="A" start="4">    - Letters starts with D.

Example

Following is an example where we used <ol type=”i” start=”4″ >

<!DOCTYPE html>
<html>
<head>
<title>HTML Ordered List</title>
</head>
<body>
   <ol type="i" start="4">
   <li>Beetroot</li>
   <li>Ginger</li>
   <li>Potato</li>
   <li>Radish</li>
   </ol>
</body>
</html>

This will produce following result:

  1. Beetroot
  2. Ginger
  3. Potato
  4. Radish

HTML Definition Lists

HTML and XHTML support a list style which is called definition lists where entries are listed like in a dictionary or encyclopedia. The definition list is the ideal way to present a glossary, list of terms, or other name/value list.

Definition List makes use of following three tags.

  • <dl> – Defines the start of the list
  • <dt> – A term
  • <dd> – Term definition
  • </dl> – Defines the end of the list

Example

<!DOCTYPE html>
<html>
<head>
<title>HTML Definition List</title>
</head>
<body>
<dl>
<dt><b>HTML</b></dt>
<dd>This stands for Hyper Text Markup Language</dd>
<dt><b>HTTP</b></dt>
<dd>This stands for Hyper Text Transfer Protocol</dd>
</dl>
</body>
</html>

This will produce following result:

HTML
This stands for Hyper Text Markup Language
HTTP
This stands for Hyper Text Transfer Protocol

html tables

The HTML tables allow web authors to arrange data like text, images, links, other tables, etc. into rows and columns of cells.

The HTML tables are created using the <table> tag in which the <tr> tag is used to create table rows and <td> tag is used to create data cells.

Example

<!DOCTYPE html>
<html>
<head>
<title>HTML Tables</title>
</head>
<body>
<table border="1">
<tr>
<td>Row 1, Column 1</td>
<td>Row 1, Column 2</td>
</tr>
<tr>
<td>Row 2, Column 1</td>
<td>Row 2, Column 2</td>
</tr>
</table>
</body>
</html>

This will produce following result:

Row 1, Column 1 Row 1, Column 2
Row 2, Column 1 Row 2, Column 2

Here border is an attribute of <table> tag and it is used to put a border across all the cells. If you do not need a border then you can use border=”0″.

Table Heading

Table heading can be defined using <th> tag. This tag will be put to replace <td> tag, which is used to represent actual data cell. Normally you will put your top row as table heading as shown below, otherwise you can use <th> element in any row.

Example

<!DOCTYPE html>
<html>
<head>
<title>HTML Table Header</title>
</head>
<body>
<table border="1">
<tr>
<th>Name</th>
<th>Salary</th>
</tr>
<tr>
<td>Ramesh Raman</td>
<td>5000</td>
</tr>
<tr>
<td>Shabbir Hussein</td>
<td>7000</td>
</tr>
</table>
</body>
</html>

This will produce following result:

Name Salary
Ramesh Raman 5000
Shabbir Hussein 7000

Cellpadding and Cellspacing Attributes

There are two attribiutes called cellpadding and cellspacing which you will use to adjust the white space in your table cells. The cellspacing attribute defines the width of the border, while cellpadding represents the distance between cell borders and the content within a cell.

Example

<!DOCTYPE html>
<html>
<head>
<title>HTML Table Cellpadding</title>
</head>
<body>
<table border="1" cellpadding="5" cellspacing="5">
<tr>
<th>Name</th>
<th>Salary</th>
</tr>
<tr>
<td>Ramesh Raman</td>
<td>5000</td>
</tr>
<tr>
<td>Shabbir Hussein</td>
<td>7000</td>
</tr>
</table>
</body>
</html>

This will produce following result:

Name Salary
Ramesh Raman 5000
Shabbir Hussein 7000

Colspan and Rowspan Attributes

You will use colspan attribute if you want to merge two or more columns into a single column. Similar way you will use rowspan if you want to merge two or more rows.

Example

<!DOCTYPE html>
<html>
<head>
<title>HTML Table Colspan/Rowspan</title>
</head>
<body>
<table border="1">
<tr>
<th>Column 1</th>
<th>Column 2</th>
<th>Column 3</th>
</tr>
<tr><td rowspan="2">Row 1 Cell 1</td><td>Row 1 Cell 2</td><td>Row 1 Cell 3</td></tr>
<tr><td>Row 2 Cell 2</td><td>Row 2 Cell 3</td></tr>
<tr><td colspan="3">Row 3 Cell 1</td></tr>
</table>
</body>
</html>

This will produce following result:

Column 1 Column 2 Column 3
Row 1 Cell 1 Row 1 Cell 2 Row 1 Cell 3
Row 2 Cell 2 Row 2 Cell 3
Row 3 Cell 1

Tables Backgrounds

You can set table background using one of the following two ways:

  • bgcolor attribute – You can set background color for whole table or just for one cell.

  • background attribute – You can set background image for whole table or just for one cell.

You can also set border color also using bordercolor attribute.

Example

<!DOCTYPE html>
<html>
<head>
<title>HTML Table Background</title>
</head>
<body>
<table border="1" bordercolor="green" bgcolor="yellow">
<tr>
<th>Column 1</th>
<th>Column 2</th>
<th>Column 3</th>
</tr>
<tr><td rowspan="2">Row 1 Cell 1</td><td>Row 1 Cell 2</td><td>Row 1 Cell 3</td></tr>
<tr><td>Row 2 Cell 2</td><td>Row 2 Cell 3</td></tr>
<tr><td colspan="3">Row 3 Cell 1</td></tr>
</table>
</body>
</html>

This will produce following result:

Column 1 Column 2 Column 3
Row 1 Cell 1 Row 1 Cell 2 Row 1 Cell 3
Row 2 Cell 2 Row 2 Cell 3
Row 3 Cell 1

Here is an example of using background attribute. Here we will use an image available in /images directory.

<!DOCTYPE html>
<html>
<head>
<title>HTML Table Background</title>
</head>
<body>
<table border="1" bordercolor="green" background="/images/test.png">
<tr>
<th>Column 1</th>
<th>Column 2</th>
<th>Column 3</th>
</tr>
<tr><td rowspan="2">Row 1 Cell 1</td><td>Row 1 Cell 2</td><td>Row 1 Cell 3</td></tr>
<tr><td>Row 2 Cell 2</td><td>Row 2 Cell 3</td></tr>
<tr><td colspan="3">Row 3 Cell 1</td></tr>
</table>
</body>
</html>

This will produce following result. Here background image did not apply to table’s header.

Column 1 Column 2 Column 3
Row 1 Cell 1 Row 1 Cell 2 Row 1 Cell 3
Row 2 Cell 2 Row 2 Cell 3
Row 3 Cell 1

Table Height and Width

You can set a table width and height using width and height attrubutes. You can specify table width or height in terms of pixels or in terms of percentage of available screen area.

Example

<!DOCTYPE html>
<html>
<head>
<title>HTML Table Width/Height</title>
</head>
<body>
<table border="1" width="400" height="150">
<tr>
<td>Row 1, Column 1</td>
<td>Row 1, Column 2</td>
</tr>
<tr>
<td>Row 2, Column 1</td>
<td>Row 2, Column 2</td>
</tr>
</table>
</body>
</html>

This will produce following result:

Row 1, Column 1 Row 1, Column 2
Row 2, Column 1 Row 2, Column 2

Table Caption

The caption tag will serve as a title or explanation for the table and it shows up at the top of the table. This tag is deprecated in newer version of HTML/XHTML.

Example

<!DOCTYPE html>
<html>
<head>
<title>HTML Table Caption</title>
</head>
<body>
<table border="1" width="100%">
<caption>This is the caption</caption>
<tr>
<td>row 1, column 1</td><td>row 1, columnn 2</td>
</tr>
<tr>
<td>row 2, column 1</td><td>row 2, columnn 2</td>
</tr>
</table>
</body>
</html>

This will produce following result:

This is the caption
row 1, column 1 row 1, columnn 2
row 2, column 1 row 2, columnn 2

Table Header, Body, and Footer

Tables can be divided into three portions: a header, a body, and a foot. The head and foot are rather similar to headers and footers in a word-processed document that remain the same for every page, while the body is the main content holder of the table.

The three elements for separating the head, body, and foot of a table are:

  • <thead> – to create a separate table header.
  • <tbody> – to indicate the main body of the table.
  • <tfoot> – to create a separate table footer.

A table may contain several <tbody> elements to indicate different pages or groups of data. But it is notable that <thead> and <tfoot> tags should appear before <tbody>

Example

<!DOCTYPE html>
<html>
<head>
<title>HTML Table</title>
</head>
<body>
<table border="1" width="100%">
<thead>
<tr>
<td colspan="4">This is the head of the table</td>
</tr>
</thead>
<tfoot>
<tr>
<td colspan="4">This is the foot of the table</td>
</tr>
</tfoot>
<tbody>
<tr>
<td>Cell 1</td>
<td>Cell 2</td>
<td>Cell 3</td>
<td>Cell 4</td>
</tr>
</tbody>
</table>
</body>
</html>

This will produce following result:

This is the head of the table
This is the foot of the table
Cell 1 Cell 2 Cell 3 Cell 4

Nested Tables

You can use one table inside another table. Not only tables you can use almost all the tags inside table data tag <td>.

Example

Following is the example of using another table and other tags inside a table cell.

<!DOCTYPE html>
<html>
<head>
<title>HTML Table</title>
</head>
<body>
<table border="1" width="100%">
<tr>
<td>
   <table border="1" width="100%">
   <tr>
   <th>Name</th>
   <th>Salary</th>
   </tr>
   <tr>
   <td>Ramesh Raman</td>
   <td>5000</td>
   </tr>
   <tr>
   <td>Shabbir Hussein</td>
   <td>7000</td>
   </tr>
   </table>
</td>
</tr>
</table>
</body>
</html>

This will produce following result:

Name Salary
Ramesh Raman 5000
Shabbir Hussein 7000

html images

Images are very important to beautify as well as to depict many complex concepts in simple way on your web page. This tutorial will take you through simple steps to use images in your web pages.

Insert Image

You can insert any image in your web page by using <img> tag. Following is the simple syntax to use this tag.

<img src="Image URL" ... attributes-list/>

The <img> tag is an empty tag, which means that it can contain only list of attributes and it has no closing tag.

Example

To try following example, let’s keep our HTML file test.htm and image file test.png in the same directory:

<!DOCTYPE html>
<html>
<head>
<title>Using Image in Webpage</title>
</head>
<body>
<p>Simple Image Insert</p>
<img src="/html/images/test.png" alt="Test Image" />
</body>
</html>

This will produce following result:

Simple Image Insert

Test Image

You can use PNG, JPEG or GIF image file based on your comfort but make sure you specify correct image file name in src attribute. Image name is always case sensitive.

The alt attribute is a mandatory attribute which specifies an alternate text for an image, if the image cannot be displayed.

Set Image Location

Usually we keep our all the images in a separate directory. So let’s keep HTML file test.htm in our home directory and create a subdirectory images inside the home directory where we will keep our image test.png.

Example

Assuming our image location is “/html/image/test.png”, try the following example:

<!DOCTYPE html>
<html>
<head>
<title>Using Image in Webpage</title>
</head>
<body>
<p>Simple Image Insert</p>
<img src="/html/images/test.png" alt="Test Image" />
</body>
</html>

This will produce following result:

Simple Image Insert

Test Image

Set Image Width/Height

You can set image width and height based on your requirement using width and height attributes. You can specify width and height of the image in terms of either pixels or percentage of its actual size.

Example

<!DOCTYPE html>
<html>
<head>
<title>Set Image Width and Height</title>
</head>
<body>
<p>Setting image width and height</p>
<img src="/html/images/test.png" alt="Test Image" width="150" height="100"/>
</body>
</html>

This will produce following result:

Setting image width and height

Test Image

Set Image Border

By default image will have a border around it, you can specify border thickness in terms of pixels using border attribute. A thickness of 0 means, no border around the picture.

Example

<!DOCTYPE html>
<html>
<head>
<title>Set Image Border</title>
</head>
<body>
<p>Setting image Border</p>
<img src="/html/images/test.png" alt="Test Image" border="3"/>
</body>
</html>

This will produce following result:

Setting image Border

Test Image

Set Image Alignment

By default image will align at the left side of the page, but you can use align attribute to set it in the center or right.

Example

<!DOCTYPE html>
<html>
<head>
<title>Set Image Alignment</title>
</head>
<body>
<p>Setting image Alignment</p>
<img src="/html/images/test.png" alt="Test Image" border="3" align="right"/>
</body>
</html>

This will produce following result:

Setting image Alignment

Test Image

Free Web Graphics

For Free Web Graphics including patterns you can look into Free Web Graphics

html comments

Comment is a piece of code which is ignored by any web browser. It is a good practice to add comments into your HTML code, especially in complex documents, to indicate sections of a document, and any other notes to anyone looking at the code. Comments help you and others understand your code and increases code readability.

HTML comments are placed in between <!– … –> tags. So any content placed with-in <!– … –> tags will be treated as comment and will be completely ignored by the browser.

Example

<!DOCTYPE html>
<html>
<head>  <!-- Document Header Starts -->
<title>This is document title</title>
</head> <!-- Document Header Ends -->
<body>
<p>Document content goes here.....</p>
</body>
</html>

This will produce following result without displaying the content given as a part of comments:

Document content goes here…..

Valid vs Invalid Comments

Comments do not nest which means a comment can not be put inside another comment. Second the double-dash sequence “–” may not appear inside a comment except as part of the closing –> tag. You must also make sure that there are no spaces in the start-of-comment string.

Example

Here given comment is a valid comment and will be wiped off by the browser.

<!DOCTYPE html>
<html>
<head>
<title>Valid Comment Example</title>
</head>
<body>
<!--   This is valid comment -->
<p>Document content goes here.....</p>
</body>
</html>

But following line is not a valid comment and will be displayed by the browser. This is because there is a space between the left angle bracket and the exclamation mark.

<!DOCTYPE html>
<html>
<head>  
<title>Invalid Comment Example</title>
</head> 
<body>
< !--   This is not a valid comment -->
<p>Document content goes here.....</p>
</body>
</html>

This will produce following result:

< !– This is not a valid comment –>

Document content goes here…..

Multiline Comments

So far we have seen single line comments, but HTML supports multi-line comments as well.

You can comment multiple lines by the special beginning tag <!– and ending tag –> placed before the first line and end of the last line as shown in the given example below.

Example

<!DOCTYPE html><html>
<head>  
<title>Multiline Comments</title>
</head> 
<body>
<!--   
This is a multiline comment and it can
span through as many as lines you like.
-->
<p>Document content goes here.....</p>
</body>
</html>

This will produce following result:

Document content goes here…..

Conditional Comments

Conditional comments only work in Internet Explorer (IE) on Windows but they are ignored by other browsers. They are supported from Explorer 5 onwards, and you can use them to give conditional instructions to different versions of IE.

Example

<!DOCTYPE html><html>
<head>  
<title>Conditional Comments</title>

<!--[if IE 6]>
   Special instructions for IE 6 here
<![endif]-->

</head> 
<body>
<p>Document content goes here.....</p>
</body>
</html>

You will come across a situation where you will need to apply a different style sheet based on different versions of Internet Explorer, in such situation conditional comments will be helpful.

Using Comment Tag

There are few browsers that support <comment> tag to comment a part of HTML code.

Example

<!DOCTYPE html><html>
<head>
<title>Using Comment Tag</title>
</head>
<body>
<p>This is <comment>not</comment> Internet Explorer.</p>
</body>
</html>

If you are using IE then it will produce following result:

This is Internet Explorer.

But if you are not using IE, then it will produce following result:

This is not Internet Explorer.

Commenting Script Code

Though you will learn Javascript with HTML, in a separate tutorial, but here you must make a note that if you are using Java Script or VB Script in your HTML code then it is recommended to put that script code inside proper HTML comments so that old browsers can work properly.

Example

<!DOCTYPE html><html>
<head>
<title>Commenting Script Code</title>

 
   document.write("Hello World!")
//-->

</head>
<body>
<p>Hello , World!</p>
</body>
</html>

This will produce following result:

Hello World!

Hello , World!

Commenting Style Sheets

Though you will learn using style sheets with HTML in a separate tutorial, but here you must make a note that if you are using Casecading Style Sheet (CSS) in your HTML code then it is recommended to put that style sheet code inside proper HTML comments so that old browsers can work properly.

Example

<!DOCTYPE html><html>
<head>
<title>Commenting Style Sheets</title>
<style>
<!--
.example {
  border:1px solid #4a7d49;
}
//-->
</style>
</head>
<body>
class="example">Hello , World!
</body> </html>

This will produce following result:

Hello , World!

html meta tags

HTML lets you specify metadata – additional important information about a document in a variety of ways. The META elements can be used to include name/value pairs describing properties of the HTML document, such as author, expiry date, a list of keywords, document author etc.

The <meta> tag is used to provide such additional information. This tag is an empty element and so does not have a closing tag but it carries information within its attributes.

You can include one or more meta tags in your document based on what information you want to keep in your document but in general, meta tags do not impact physical appearance of the document so from appearance point of view, it does not matter if you include them or not.

Adding Meta Tags to Your Documents

You can add metadata to your web pages by placing <meta> tags inside the header of the document which is represented by <head> and </head> tags. A meta tag can have following attributes in addition to core attributes:

Attribute Description
Name Name for the property. Can be anything. Examples include, keywords, description, author, revised, generator etc.
content Specifies the property’s value.
scheme Specifies a scheme to interpret the property’s value (as declared in the content attribute).
http-equiv Used for http response message headers. For example http-equiv can be used to refresh the page or to set a cookie. Values include content-type, expires, refresh and set-cookie.

Specifying Keywords

You can use <meta> tag to specify important keywords related to the document and later these keywords are used by the search engines while indexing your webpage for searching purpose.

Example

Following is an example where we are adding HTML, Meta Tags, Metadata as important keywords about the document.

<!DOCTYPE html>
<html>
<head>
<title>Meta Tags Example</title>
<meta name="keywords" content="HTML, Meta Tags, Metadata" />
</head>
<body>
<p>Hello HTML5!</p>
</body>
</html>

This will produce following result:

Hello HTML5!

Document Description

You can use <meta> tag to give a short description about the document. This again can be used by various search engines while indexing your webpage for searching purpose.

Example

<!DOCTYPE html>
<html>
<head>
<title>Meta Tags Example</title>
<meta name="keywords" content="HTML, Meta Tags, Metadata" />
<meta name="description" content="Learning about Meta Tags." />
</head>
<body>
<p>Hello HTML5!</p>
</body>
</html>

Document Revision Date

You can use <meta> tag to give information about when last time the document was updated. This information can be used by various web browsers while refreshing your webpage.

Example

<!DOCTYPE html>
<html>
<head>
<title>Meta Tags Example</title>
<meta name="keywords" content="HTML, Meta Tags, Metadata" />
<meta name="description" content="Learning about Meta Tags." />
<meta name="revised" content="Tutorialspoint, 3/7/2014" />
</head>
<body>
<p>Hello HTML5!</p>
</body>
</html>

Document Refreshing

A <meta> tag can be used to specify a duration after which your web page will keep refreshing automatically.

Example

If you want your page keep refreshing after every 5 seconds then use the following syntax.

<!DOCTYPE html>
<html>
<head>
<title>Meta Tags Example</title>
<meta name="keywords" content="HTML, Meta Tags, Metadata" />
<meta name="description" content="Learning about Meta Tags." />
<meta name="revised" content="Tutorialspoint, 3/7/2014" />
<meta http-equiv="refresh" content="5" />
</head>
<body>
<p>Hello HTML5!</p>
</body>
</html>

Page Redirection

You can use <meta> tag to redirect your page to any other webpage. You can also specify a duration if you want to redirect the page after a certain number of seconds.

Example

Following is an example of redirecting current page to another page after 5 seconds. If you want to redirect page immediately then do not specify content attribute.

<!DOCTYPE html>
<html>
<head>
<title>Meta Tags Example</title>
<meta name="keywords" content="HTML, Meta Tags, Metadata" />
<meta name="description" content="Learning about Meta Tags." />
<meta name="revised" content="Tutorialspoint, 3/7/2014" />
<meta http-equiv="refresh" content="5; url=https://www.tutorialspoint.com" />
</head>
<body>
<p>Hello HTML5!</p>
</body>
</html>

Setting Cookies

Cookies are data, stored in small text files on your computer and it is exchanged between web browser and web server to keep track of various information based on your web application need.

You can use <meta> tag to store cookies on client side and later this information can be used by the Web Server to track a site visitor.

Example

Following is an example of Setting Cookies.

<!DOCTYPE html>
<html>
<head>
<title>Meta Tags Example</title>
<meta name="keywords" content="HTML, Meta Tags, Metadata" />
<meta name="description" content="Learning about Meta Tags." />
<meta name="revised" content="Tutorialspoint, 3/7/2014" />
<meta http-equiv="cookie" content="userid=xyz; expires=Wednesday, 08-Aug-15 23:59:59 GMT;" />
</head>
<body>
<p>Hello HTML5!</p>
</body>
</html>

If you do not include the expiration date and time, the cookie is considered a session cookie and will be deleted when the user exits the browser.

Note: You can check PHP and Cookiestutorial for a complete detail on Cookies.

Setting Author Name

You can set an author name in a web page using meta tag. See an example below:

Example

<!DOCTYPE html>
<html>
<head>
<title>Meta Tags Example</title>
<meta name="keywords" content="HTML, Meta Tags, Metadata" />
<meta name="description" content="Learning about Meta Tags." />
<meta name="author" content="Mahnaz Mohtashim" />
</head>
<body>
<p>Hello HTML5!</p>
</body>
</html>

Specify Character Set

You can use <meta> tag to specify character set used within the webpage.

Example

By default, Web servers and Web browsers use ISO-8859-1 (Latin1) encoding to process Web pages. Following is an example to set UTF-8 encoding:

<!DOCTYPE html>
<html>
<head>
<title>Meta Tags Example</title>
<meta name="keywords" content="HTML, Meta Tags, Metadata" />
<meta name="description" content="Learning about Meta Tags." />
<meta name="author" content="Mahnaz Mohtashim" />
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<p>Hello HTML5!</p>
</body>
</html>

To serve the static page with traditional Chinese characters, the webpage must contain a <meta> tag to set Big5 encoding:

<!DOCTYPE html>
<html>
<head>
<title>Meta Tags Example</title>
<meta name="keywords" content="HTML, Meta Tags, Metadata" />
<meta name="description" content="Learning about Meta Tags." />
<meta name="author" content="Mahnaz Mohtashim" />
<meta http-equiv="Content-Type" content="text/html; charset=Big5" />
</head>
<body>
<p>Hello HTML5!</p>
</body>
</html>

html phrase tags

The phrase tags have been designed for specific purposes, though they are displayed in a similar way as other basic tags like <b>, <i>, <pre>, and <tt>, you have seen in previous chapter. This chapter will take you through all the important phrase tags, so let’s start seeing them one by one.

Emphasized Text

Anything that appears within <em>…</em> element is displayed as emphasized text.

Example

<!DOCTYPE html>
<html>
<head>
<title>Emphasized Text Example</title>
</head>
<body>
<p>The following word uses a <em>emphasized</em> typeface.</p>
</body>
</html>

This will produce following result:

The following word uses a emphasized typeface.

Marked Text

Anything that appears with-in <mark>…</mark> element, is displayed as marked with yellow ink.

Example

<!DOCTYPE html>
<html>
<head>
<title>Marked Text Example</title>
</head>
<body>
<p>The following word has been <mark>marked</mark> with yellow</p>
</body>
</html>

This will produce following result:

The following word has been marked with yellow.

Strong Text

Anything that appears within <strong>…</strong> element is displayed as important text.

Example

<!DOCTYPE html>
<html>
<head>
<title>Strong Text Example</title>
</head>
<body>
<p>The following word uses a <strong>strong</strong> typeface.</p>
</body>
</html>

This will produce following result:

The following word uses a strong typeface.

Text Abbreviation

You can abbreviate a text by putting it inside opening <abbr> and closing </abbr> tags. If present, the title attribute must contain this full description and nothing else.

Example

<!DOCTYPE html>
<html>
<head>
<title>Text Abbreviation</title>
</head>
<body>
<p>My best friend's name is  <abbr title="Abhishek">Abhy</abbr>.</p>
</body>
</html>

This will produce following result:

My best friend’s name is Abhy.

Acronym Element

The <acronym> element allows you to indicate that the text between <acronym> and </acronym> tags is an acronym.

At present, the major browsers do not change the appearance of the content of the <acronym> element.

Example

<!DOCTYPE html>
<html>
<head>
<title>Acronym Example</title>
</head>
<body>
<p>This chapter covers marking up text in <acronym>XHTML</acronym>.</p>
</body>
</html>

This will produce following result:

This chapter covers marking up text in XHTML.

Text Direction

The <bdo>…</bdo> element stands for Bi-Directional Override and it is used to override the current text direction.

Example

<!DOCTYPE html>
<html>
<head>
<title>Text Direction Example</title>
</head>
<body>
<p>This text will go left to right.</p>
<p><bdo dir="rtl">This text will go right to left.</bdo></p>
</body>
</html>

This will produce following result:

This text will go left to right.

This text will go right to left.

Special Terms

The <dfn>…</dfn> element (or HTML Definition Element) allows you to specify that you are introducing a special term. It’s usage is similar to italic words in the midst of a paragraph.

Typically, you would use the <dfn> element the first time you introduce a key term. Most recent browsers render the content of a <dfn> element in an italic font.

Example

<!DOCTYPE html>
<html>
<head>
<title>Special Terms Example</title>
</head>
<body>
<p>The following word is a <dfn>special</dfn> term.</p>
</body>
</html>

This will produce following result:

The following word is a special term.

Quoting Text

When you want to quote a passage from another source, you should put it in between <blockquote>…</blockquote> tags.

Text inside a <blockquote> element is usually indented from the left and right edges of the surrounding text, and sometimes uses an italicized font.

Example

<!DOCTYPE html>
<html>
<head>
<title>Blockquote Example</title>
</head>
<body>
<p>The following description of XHTML is taken from the W3C Web site:</p>

<blockquote>XHTML 1.0 is the W3C's first Recommendation for XHTML, following on from earlier work on HTML 4.01, HTML 4.0, HTML 3.2 and HTML 2.0.</blockquote>
</body>
</html>

This will produce following result:

The following description of XHTML is taken from the W3C Web site:

XHTML 1.0 is the W3C’s first Recommendation for XHTML, following on from earlier work on HTML 4.01, HTML 4.0, HTML 3.2 and HTML 2.0.

Short Quotations

The <q>…</q> element is used when you want to add a double quote within a sentence.

Example

<!DOCTYPE html>
<html>
<head>
<title>Double Quote Example</title>
</head>
<body>
<p>Amit is in Spain, <q>I think I am wrong</q>.</p>
</body>
</html>

This will produce following result:

Amit is in Spain, I think I am wrong.

Text Citations

If you are quoting a text, you can indicate the source placing it between an opening <cite> tag and closing </cite> tag

As you would expect in a print publication, the content of the <cite> element is rendered in italicized text by default.

Example

<!DOCTYPE html>
<html>
<head>
<title>Citations Example</title>
</head>
<body>
<p>This HTML tutorial is derived from <cite>W3 Standard for HTML</cite>.</p>
</body>
</html>

This will produce following result:

This HTML tutorial is derived from W3 Standard for HTML.

Computer Code

Any programming code to appear on a Web page should be placed inside <code>…</code> tags. Usually the content of the <code> element is presented in a monospaced font, just like the code in most programming books.

Example

<!DOCTYPE html>
<html>
<head>
<title>Computer Code Example</title>
</head>
<body>
<p>Regular text. <code>This is code.</code> Regular text.</p>
</body>
</html>

This will produce following result:

Regular text. This is code. Regular text.

Keyboard Text

When you are talking about computers, if you want to tell a reader to enter some text, you can use the <kbd>…</kbd> element to indicate what should be typed in, as in this example.

Example

<!DOCTYPE html>
<html>
<head>
<title>Keyboard Text Example</title>
</head>
<body>
<p>Regular text. <kbd>This is inside kbd element</kbd> Regular text.</p>
</body>
</html>

This will produce following result:

Regular text. This is inside kbd element Regular text.

Programming Variables

This element is usually used in conjunction with the <pre> and <code> elements to indicate that the content of that element is a variable.

Example

<!DOCTYPE html>
<html>
<head>
<title>Variable Text Example</title>
</head>
<body>
<p><code>document.write("<var>user-name</var>")</code></p>
</body>
</html>

This will produce following result:

document.write("user-name")

Program Output

The <samp>…</samp> element indicates sample output from a program, and script etc. Again, it is mainly used when documenting programming or coding concepts.

Example

<!DOCTYPE html>
<html>
<head>
<title>Program Output Example</title>
</head>
<body>
<p>Result produced by the program is <samp>Hello World!</samp></p>
</body>
</html>

This will produce following result:

Result produced by the program is Hello World!

Address Text

The <address>…</address> element is used to contain any address.

Example

<!DOCTYPE html>
<html>
<head>
<title>Address Example</title>
</head>
<body>
<address>388A, Road No 22, Jubilee Hills -  Hyderabad</address>
</body>
</html>

This will produce following result:

388A, Road No 22, Jubilee Hills – Hyderabad

html formatting

If you use a word processor, you must be familiar with the ability to make text bold, italicized, or underlined; these are just three of the ten options available to indicate how text can appear in HTML and XHTML.

Bold Text

Anything that appears within <b>…</b> element, is displayed in bold as shown below:

Example

<!DOCTYPE html>
<html>
<head>
<title>Bold Text Example</title>
</head>
<body>
<p>The following word uses a <b>bold</b> typeface.</p>
</body>
</html>

This will produce following result:

The following word uses a bold typeface.

Italic Text

Anything that appears within <i>…</i> element is displayed in italicized as shown below:

Example

<!DOCTYPE html>
<html>
<head>
<title>Italic Text Example</title>
</head>
<body>
<p>The following word uses a <i>italicized</i> typeface.</p>
</body>
</html>

This will produce following result:

The following word uses a italicized typeface.

Underlined Text

Anything that appears within <u>…</u> element, is displayed with underline as shown below:

Example

<!DOCTYPE html>
<html>
<head>
<title>Underlined Text Example</title>
</head>
<body>
<p>The following word uses a <u>underlined</u> typeface.</p>
</body>
</html>

This will produce following result:

The following word uses a underlined typeface.

Strike Text

Anything that appears within <strike>…</strike> element is displayed with strikethrough, which is a thin line through the text as shown below:

Example

<!DOCTYPE html>
<html>
<head>
<title>Strike Text Example</title>
</head>
<body>
<p>The following word uses a <strike>strikethrough</strike> typeface.</p>
</body>
</html>

This will produce following result:

The following word uses a strikethrough typeface.

Monospaced Font

The content of a <tt>…</tt> element is written in monospaced font. Most of the fonts are known as variable-width fonts because different letters are of different widths (for example, the letter ‘m’ is wider than the letter ‘i’). In a monospaced font, however, each letter has the same width.

Example

<!DOCTYPE html>
<html>
<head>
<title>Monospaced Font Example</title>
</head>
<body>
<p>The following word uses a <tt>monospaced</tt> typeface.</p>
</body>
</html>

This will produce following result:

The following word uses a monospaced typeface.

Superscript Text

The content of a <sup>…</sup> element is written in superscript; the font size used is the same size as the characters surrounding it but is displayed half a character’s height above the other characters.

Example

<!DOCTYPE html>
<html>
<head>
<title>Superscript Text Example</title>
</head>
<body>
<p>The following word uses a <sup>superscript</sup> typeface.</p>
</body>
</html>

This will produce following result:

The following word uses a superscripttypeface.

Subscript Text

The content of a <sub>…</sub> element is written in subscript; the font size used is the same as the characters surrounding it, but is displayed half a character’s height beneath the other characters.

Example

<!DOCTYPE html>
<html>
<head>
<title>Subscript Text Example</title>
</head>
<body>
<p>The following word uses a <sub>subscript</sub> typeface.</p>
</body>
</html>

This will produce following result:

The following word uses a subscript typeface.

Inserted Text

Anything that appears within <ins>…</ins> element is displayed as inserted text.

Example

<!DOCTYPE html>
<html>
<head>
<title>Inserted Text Example</title>
</head>
<body>
<p>I want to drink <del>cola</del> <ins>wine</ins></p>
</body>
</html>

This will produce following result:

I want to drink cola wine

Deleted Text

Anything that appears within <del>…</del> element, is displayed as deleted text.

Example

<!DOCTYPE html>
<html>
<head>
<title>Deleted Text Example</title>
</head>
<body>
<p>I want to drink <del>cola</del> <ins>wine</ins></p>
</body>
</html>

This will produce following result:

I want to drink cola wine

Larger Text

The content of the <big>…</big> element is displayed one font size larger than the rest of the text surrounding it as shown below:

Example

<!DOCTYPE html>
<html>
<head>
<title>Larger Text Example</title>
</head>
<body>
<p>The following word uses a <big>big</big> typeface.</p>
</body>
</html>

This will produce following result:

The following word uses a big typeface.

Smaller Text

The content of the <small>…</small> element is displayed one font size smaller than the rest of the text surrounding it as shown below:

Example

<!DOCTYPE html>
<html>
<head>
<title>Smaller Text Example</title>
</head>
<body>
<p>The following word uses a <small>small</small> typeface.</p>
</body>
</html>

This will produce following result:

The following word uses a small typeface.

Grouping Content

The 

 and  elements allow you to group together several elements to create sections or subsections of a page.

For example, you might want to put all of the footnotes on a page within a

element to indicate that all of the elements within that

element relate to the footnotes. You might then attach a style to this

element so that they appear using a special set of style rules.

Example




Div Tag Example




id="content" align="left" bgcolor="white">
Content Articles

Actual content goes here.....

</body> </html>

This will produce following result:

CONTENT ARTICLES

Actual content goes here…..

The <span> element, on the other hand, can be used to group inline elements only. So, if you have a part of a sentence or paragraph which you want to group together, you could use the <span> element as follows

Example

<!DOCTYPE html>
<html>
<head>
<title>Span Tag Example</title>
</head>
<body>
<p>This is the example of <span style="color:green">span tag</span> and the <span style="color:red">div tag</span> alongwith CSS</p>
</body>
</html>

This will produce following result:

This is the example of span tag and the div tag alongwith CSS

These tags are commonly used with CSS to allow you to attach a style to a section of a page.

html attributes

We have seen few HTML tags and their usage like heading tags <h1>, <h2>, paragraph tag <p> and other tags. We used them so far in their simplest form, but most of the HTML tags can also have attributes, which are extra bits of information.

An attribute is used to define the characteristics of an HTML element and is placed inside the element’s opening tag. All attributes are made up of two parts: a name and a value:

  • The name is the property you want to set. For example, the paragraph <p> element in the example carries an attribute whose name is align, which you can use to indicate the alignment of paragraph on the page.

  • The value is what you want the value of the property to be set and always put within quotations. The below example shows three possible values of align attribute: left, center and right.

Attribute names and attribute values are case-insensitive. However, the World Wide Web Consortium (W3C) recommends lowercase attributes/attribute values in their HTML 4 recommendation.

Example

<!DOCTYPE html>
<html>
<head>
<title>Align Attribute  Example</title>
</head>
<body>
<p align="left">This is left aligned</p>
<p align="center">This is center aligned</p>
<p align="right">This is right aligned</p>
</body>
</html>

This will display following result:

This is left aligned

This is center aligned

This is right aligned

Core Attributes

The four core attributes that can be used on the majority of HTML elements (although not all) are:

  • id
  • title
  • class
  • style

The id Attribute

The id attribute of an HTML tag can be used to uniquely identify any element within an HTML page. There are two primary reasons that you might want to use an id attribute on an element:

  • If an element carries an id attribute as a unique identifier it is possible to identify just that element and its content.

  • If you have two elements of the same name within a Web page (or style sheet), you can use the id attribute to distinguish between elements that have the same name.

We will discuss style sheet in separate tutorial. For now, let’s use the id attribute to distinguish between two paragraph elements as shown below.

EXAMPLE

<p id="html">This para explains what is HTML</p>
<p id="css">This para explains what is Cascading Style Sheet</p>

The title Attribute

The title attribute gives a suggested title for the element. They syntax for the title attribute is similar as explained for id attribute:

The behavior of this attribute will depend upon the element that carries it, although it is often displayed as a tooltip when cursor comes over the element or while the element is loading.

EXAMPLE

<!DOCTYPE html>
<html>
<head>
<title>The title Attribute Example</title>
</head>
<body>
<h3 title="Hello HTML!">Titled Heading Tag Example</h3>
</body>
</html>

This will produce following result:

Titled Heading Tag Example

Now try to bring your cursor over “Titled Heading Tag Example” and you will see that whatever title you used in your code is coming out as a tooltip of the cursor.

The class Attribute

The class attribute is used to associate an element with a style sheet, and specifies the class of element. You will learn more about the use of the class attribute when you will learn Cascading Style Sheet (CSS). So for now you can avoid it.

The value of the attribute may also be a space-separated list of class names. For example:

class="className1 className2 className3"

The style Attribute

The style attribute allows you to specify Cascading Style Sheet (CSS) rules within the element.

<!DOCTYPE html>
<html>
<head>
<title>The style Attribute</title>
</head>
<body>
<p style="font-family:arial; color:#FF0000;">Some text...</p>
</body>
</html>

This will produce following result:

Some text…

At this point of time, we are not learning CSS, so just let’s proceed without bothering much about CSS. Here you need to understand what are HTML attributes and how they can be used while formatting content.

Internationalization Attributes

There are three internationalization attributes, which are available for most (although not all) XHTML elements.

  • dir
  • lang
  • xml:lang

The dir Attribute

The dir attribute allows you to indicate to the browser the direction in which the text should flow. The dir attribute can take one of two values, as you can see in the table that follows:

Value Meaning
ltr Left to right (the default value)
rtl Right to left (for languages such as Hebrew or Arabic that are read right to left)

EXAMPLE

<!DOCTYPE html>
<html dir="rtl">
<head>
<title>Display Directions</title>
</head>
<body>
This is how IE 5 renders right-to-left directed text.
</body>
</html>

This will produce following result:

This is how IE 5 renders right-to-left directed text.

When dir attribute is used within the <html> tag, it determines how text will be presented within the entire document. When used within another tag, it controls the text’s direction for just the content of that tag.

The lang Attribute

The lang attribute allows you to indicate the main language used in a document, but this attribute was kept in HTML only for backwards compatibility with earlier versions of HTML. This attribute has been replaced by the xml:lang attribute in new XHTML documents.

The values of the lang attribute are ISO-639 standard two-character language codes. Check HTML Language Codes: ISO 639for a complete list of language codes.

EXAMPLE

<!DOCTYPE html>
<html lang="en">
<head>
<title>English Language Page</title>
</head>
<body>
This page is using English Language
</body>
</html>

The xml:lang Attribute

The xml:lang attribute is the XHTML replacement for the lang attribute. The value of the xml:lang attribute should be an ISO-639 country code as mentioned in previous section.

Generic Attributes

Here’s a table of some other attributes that are readily usable with many of the HTML tags.

Attribute Options Function
align right, left, center Horizontally aligns tags
valign top, middle, bottom Vertically aligns tags within an HTML element.
bgcolor numeric, hexidecimal, RGB values Places a background color behind an element
background URL Places a background image behind an element
id User Defined Names an element for use with Cascading Style Sheets.
class User Defined Classifies an element for use with Cascading Style Sheets.
width Numeric Value Specifies the width of tables, images, or table cells.
height Numeric Value Specifies the height of tables, images, or table cells.
title User Defined “Pop-up” title of the elements.

We will see related examples as we will proceed to study other HTML tags. For a complete list of HTML Tags and related attributes please check reference to HTML Tags List.