Encyclopedia

TCP/IP Tutorial

2008-03-30T23:56:00.000-07:00

TCP/IP Tutorial
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TCP/IP is the communication protocol for the Internet.

In this tutorial you will learn what TCP/IP is, and how it works.

TCP/IP is the Internet Communication Protocol

A communication protocol is a description of the rules computers must follow to communicate with each other. The Internet communication protocol defines the rules for computer communication over the Internet.
Your Browser and Your Server Use TCP/IP

Internet browsers and Internet servers use TCP/IP to connect to the Internet. Your browser uses TCP/IP to access Internet servers, and servers use TCP/IP to send HTML back to your browser.
Your E-Mail Uses TCP/IP

Your e-mail program uses TCP/IP to connect to the Internet for sending and receiving e-mails.
Your Internet Address is TCP/IP

Your Internet address "59.92.189.13" is a part of the standard TCP/IP protocol. (And so is your domain name "www.someonesplace.com")

HTML Color Names

2008-03-25T03:01:00.000-07:00

HTML Colors

The table below provides a list of the color names that are supported by all major browsers.

Note: If you want your pages to validate with an HTML or a CSS validator, W3C has listed 16 color names that you can use: aqua, black, blue, fuchsia, gray, green, lime, maroon, navy, olive, purple, red, silver, teal, white, and yellow. If you want to use other colors, you must specify their RGB or HEX value.

Click on a color name (or a hex value) to view the color as the background-color along with different text colors:
Color Name Color HEX Color
AliceBlue #F0F8FF
AntiqueWhite #FAEBD7
Aqua #00FFFF
Aquamarine #7FFFD4
Azure #F0FFFF
Beige #F5F5DC
Bisque #FFE4C4
Black #000000
BlanchedAlmond #FFEBCD
Blue #0000FF
BlueViolet #8A2BE2
Brown #A52A2A
BurlyWood #DEB887
CadetBlue #5F9EA0
Chartreuse #7FFF00
Chocolate #D2691E
Coral #FF7F50
CornflowerBlue #6495ED
Cornsilk #FFF8DC
Crimson #DC143C
Cyan #00FFFF
DarkBlue #00008B
DarkCyan #008B8B
DarkGoldenRod #B8860B
DarkGray #A9A9A9
DarkGrey #A9A9A9
DarkGreen #006400
DarkKhaki #BDB76B
DarkMagenta #8B008B
DarkOliveGreen #556B2F
Darkorange #FF8C00
DarkOrchid #9932CC
DarkRed #8B0000
DarkSalmon #E9967A
DarkSeaGreen #8FBC8F
DarkSlateBlue #483D8B
DarkSlateGray #2F4F4F
DarkSlateGrey #2F4F4F
DarkTurquoise #00CED1
DarkViolet #9400D3
DeepPink #FF1493
DeepSkyBlue #00BFFF
DimGray #696969
DimGrey #696969
DodgerBlue #1E90FF
FireBrick #B22222
FloralWhite #FFFAF0
ForestGreen #228B22
Fuchsia #FF00FF
Gainsboro #DCDCDC
GhostWhite #F8F8FF
Gold #FFD700
GoldenRod #DAA520
Gray #808080
Grey #808080
Green #008000
GreenYellow #ADFF2F
HoneyDew #F0FFF0
HotPink #FF69B4
IndianRed #CD5C5C
Indigo #4B0082
Ivory #FFFFF0
Khaki #F0E68C
Lavender #E6E6FA
LavenderBlush #FFF0F5
LawnGreen #7CFC00
LemonChiffon #FFFACD
LightBlue #ADD8E6
LightCoral #F08080
LightCyan #E0FFFF
LightGoldenRodYellow #FAFAD2
LightGray #D3D3D3
LightGrey #D3D3D3
LightGreen #90EE90
LightPink #FFB6C1
LightSalmon #FFA07A
LightSeaGreen #20B2AA
LightSkyBlue #87CEFA
LightSlateGray #778899
LightSlateGrey #778899
LightSteelBlue #B0C4DE
LightYellow #FFFFE0
Lime #00FF00
LimeGreen #32CD32
Linen #FAF0E6
Magenta #FF00FF
Maroon #800000
MediumAquaMarine #66CDAA
MediumBlue #0000CD
MediumOrchid #BA55D3
MediumPurple #9370D8
MediumSeaGreen #3CB371
MediumSlateBlue #7B68EE
MediumSpringGreen #00FA9A
MediumTurquoise #48D1CC
MediumVioletRed #C71585
MidnightBlue #191970
MintCream #F5FFFA
MistyRose #FFE4E1
Moccasin #FFE4B5
NavajoWhite #FFDEAD
Navy #000080
OldLace #FDF5E6
Olive #808000
OliveDrab #6B8E23
Orange #FFA500
OrangeRed #FF4500
Orchid #DA70D6
PaleGoldenRod #EEE8AA
PaleGreen #98FB98
PaleTurquoise #AFEEEE
PaleVioletRed #D87093
PapayaWhip #FFEFD5
PeachPuff #FFDAB9
Peru #CD853F
Pink #FFC0CB
Plum #DDA0DD
PowderBlue #B0E0E6
Purple #800080
Red #FF0000
RosyBrown #BC8F8F
RoyalBlue #4169E1
SaddleBrown #8B4513
Salmon #FA8072
SandyBrown #F4A460
SeaGreen #2E8B57
SeaShell #FFF5EE
Sienna #A0522D
Silver #C0C0C0
SkyBlue #87CEEB
SlateBlue #6A5ACD
SlateGray #708090
SlateGrey #708090
Snow #FFFAFA
SpringGreen #00FF7F
SteelBlue #4682B4
Tan #D2B48C
Teal #008080
Thistle #D8BFD8
Tomato #FF6347
Turquoise #40E0D0
Violet #EE82EE
Wheat #F5DEB3
White #FFFFFF
WhiteSmoke #F5F5F5
Yellow #FFFF00
YellowGreen #9ACD32

Browser Statistics

2008-03-11T22:02:00.000-07:00

What is the trend in browser usage?
Web Statistics and Trends

Statistics are important information. From the statistics below, you can see that Internet Explorer is the most common browser. However, FireFox has become quite popular as well.
Browser Statistics Month by Month
2008 IE7 IE6 IE5 Fx Moz S O
February 22.0% 30.7% 1.7% 36.5% 1.1% 2.0% 1.4%
January 21.2% 32.0% 1.5% 36.4% 1.3% 1.9% 1.4%

2007 IE7 IE6 IE5 Fx Moz S O
December 21.0% 33.2% 1.7% 36.3% 1.4% 1.7% 1.4%
November 20.8% 33.6% 1.6% 36.3% 1.2% 1.8% 1.6%
October 20.7% 34.5% 1.5% 36.0% 1.3% 1.7% 1.6%
September 20.8% 34.9% 1.5% 35.4% 1.2% 1.6% 1.5%
August 20.5% 35.7% 1.5% 34.9% 1.3% 1.5% 1.7%
July 20.1% 36.9% 1.5% 34.5% 1.4% 1.5% 1.9%
June 19.7% 37.3% 1.5% 34.0% 1.4% 1.5% 1.8%
May 19.2% 38.1% 1.6% 33.7% 1.3% 1.5% 1.7%
April 19.1% 38.4% 1.7% 32.9% 1.3% 1.5% 1.6%
March 18.0% 38.7% 2.0% 31.8% 1.3% 1.6% 1.6%
February 16.4% 39.8% 2.5% 31.2% 1.4% 1.7% 1.5%
January 13.3% 42.3% 3.0% 31.0% 1.5% 1.7% 1.5%

2006 IE7 IE6 IE5 Fx Moz N7/8 O
November 7.1% 49.9% 3.6% 29.9% 2.5% 0.2% 1.5%
September 2.5% 55.6% 4.0% 27.3% 2.3% 0.4% 1.6%
July 1.9% 56.3% 4.2% 25.5% 2.3% 0.4% 1.4%
May 1.1% 57.4% 4.5% 25.7% 2.3% 0.3% 1.5%
March 0.6% 58.8% 5.3% 24.5% 2.4% 0.5% 1.5%
January 0.2% 60.3% 5.5% 25.0% 3.1% 0.5% 1.6%

2005 IE6 IE5 Fx Moz N7 O8 O7
November 62.7% 6.2% 23.6% 2.8% 0.4% 1.3% 0.2%
September 69.8% 5.7% 18.0% 2.5% 0.4% 1.0% 0.2%
July 67.9% 5.9% 19.8% 2.6% 0.5% 0.8% 0.4%
May 64.8% 6.8% 21.0% 3.1% 0.7% 0.7% 0.6%
March 63.6% 8.9% 18.9% 3.3% 1.0% 0.3% 1.6%
January 64.8% 9.7% 16.6% 3.4% 1.1% 1.9%

2004 IE6 IE5 Moz N3 N7 N4 O7
November 66.0% 10.2% 16.5% 0.2% 1.2% 0.3% 1.6%
September 67.8% 11.2% 13.7% 0.3% 1.4% 0.3% 1.7%
July 67.2% 13.2% 12.6% 0.4% 1.4% 0.4% 1.6%
May 68.1% 13.8% 9.5% 0.6% 1.4% 0.4% 1.6%
March 68.2% 14.6% 7.9% 0.8% 1.4% 0.6% 1.4%
January 68.9% 15.8% 5.5% 0.4% 1.5% 0.5% 1.5%

2003 IE6 IE5 Moz N3 N7 N4 O7
November 71.2% 13.7% 7.2% 0.5% 1.6% 0.5% 1.9%
September 69.7% 16.9% 6.2% 0.6% 1.5% 0.6% 1.8%
July 66.9% 20.3% 5.7% 0.6% 1.5% 0.6% 1.7%
May 65.0% 22.7% 4.6% 1.0% 1.4% 0.9% 1.4%
March 63.4% 24.6% 4.2% 0.9% 1.4% 1.1% 1.2%
January 55.3% 29.3% 4.0% 1.2% 1.1% 1.7%

2002 IE6 IE5 AOL N3 N5 N4 IE4
November 53.5% 29.9% 5.2% 1.1% 4.9% 2.0%
September 49.1% 34.4% 4.5% 1.3% 4.5% 2.2%
July 44.4% 40.1% 3.5% 1.2% 3.5% 2.6% 0.5%
May 40.7% 46.0% 2.8% 1.2% 2.7% 3.4% 0.7%
March 36.7% 49.4% 3.0% 1.2% 2.4% 4.1% 0.7%
January 30.1% 55.7% 2.8% 1.3% 2.2% 4.4% 1.0%

IE Internet Explorer
Fx Firefox (identified as Mozilla before 2005)
Moz The Mozilla Suite (Gecko, Netscape)
S Safari (and Konqueror. Both identified as Mozilla before 2007)
O Opera
N Netscape (identified as Mozilla after 2006)
AOL America Online (based on both Internet Explorer and Mozilla)

Browsers that count for less than 0.5% are not listed.

W3Schools is a website for people with an interest for web technologies. These people are more interested in using alternative browsers than the average user. The average user tends to use Internet Explorer, since it comes preinstalled with Windows. Most do not seek out other browsers.

These facts indicate that the browser figures above are not 100% realistic. Other web sites have statistics showing that Internet Explorer is used by at least 80% of the users.

Anyway, our data, collected from W3Schools' log-files, over a five year period, clearly shows the long and medium-term trends.
JavaScript Statistics

There are no absolute trends about the use of JavaScript. Some users have scripting turned off. Some browsers don't support scripting:
2007 JavaScript On JavaScript Off
January 94% 6%

2006
July 92% 8%
January 90% 10%

2005
July 90% 10%
January 89% 11%

2004
July 90% 10%
January 92% 8%

2003
July 89% 11%
January 89% 11%

2002
October 88% 12%

Other Statistics

Operating system statistics

Browser display statistics
Statistics Are Often Misleading

You cannot - as a web developer - rely only on statistics. Statistics can often be misleading.

Global averages may not always be relevant to your web site. Different sites attract different audiences. Some web sites attract professional developers using professional hardware, while other sites attract hobbyists using old low spec computers.

Also be aware that many statistics may have an incomplete or faulty browser detection. It is quite common by many web-stats report programs, not to detect the newest browsers.

(The statistics above are extracted from W3Schools' log-files, but we are also monitoring other sources around the Internet to assure the quality of these figures).
Quotes

"The pure and simple truth is rarely pure and never simple."
Oscar Wilde

"First get your facts; then you can distort them at your leisure."
Mark Twain

Web Hosting Tutorial

2008-03-08T19:39:00.000-08:00

Table of Contents

Introduction to Web Hosting
This chapter explains how the WWW works, how you can publish your own web site, and what an Internet service provider can offer.

Web Hosting Providers
This chapter explains the difference between hosting your web site on your own server and hosting it with an Internet service provider.

Web Hosting Domains
This chapter explains how to register your own domain name, and how to use it as your web address.

Web Hosting Capacities
This chapter explains about disk space and traffic capacities.

Web Hosting Email
This chapter explains the most common e-mail services an Internet service provider offer.

Web Hosting Technologies
This chapter explains some of the most common hosting technologies.

Web Hosting Databases
This chapter explains some of the most common web database technologies.

Web Hosting Types
This chapter explains the different types of web hosting.

Web Hosting E-commerce
This chapter describes e-commerce web hosting.

Web Hosting Resources
This chapter lists some valuable hosting resources.

MIcrosoft .net

2008-03-04T22:00:00.000-08:00

Microsoft .NET
previous next
Microsoft .NET Tutorial
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After you have studied these chapters, you will know what .NET is.

You will also know that .NET will affect the way you will create Web applications in the future.

Start learning .NET!

Table of contents

Introduction to Microsoft .NET
This introduction describes what .NET is and what it holds for the future.

Microsoft .NET Core Building Blocks
This chapter describes the core building blocks of Microsoft .NET.

Microsoft .NET Software
This chapter describes .NET development tools, software, standards and applications

Web Services
This chapter describes the concept of Web Services.

Client and Server Standards
W3Schools' own vision about .NET Client and Server Standards

Applications must be Services
W3Schools' own vision about .NET Application Services

Future Proof Applications
W3Schools' own vision about .NET and Future Proof Internet Applications

XLink and XPointer Tutorial

2008-02-19T04:05:00.000-08:00

XLink and XPointer Tutorial
XLink

Linking in XML is divided into two parts: XLink and XPointer.

XLink defines a standard way of creating hyperlinks in XML documents.

XPointer allows the hyperlinks to point to more specific parts (fragments) in the XML document.

Start learning XLink and XPointer!

Table of Contents

XLink and XPointer Introduction
This chapter explaines what the XLink and XPointer languages are.

XLink and XPointer Syntax
The syntax of XLink and XPointer.

XLink Example
An example of using XLink in an XML document.

XPointer Example
An example of using XLink and XPointer in an XML document.

XLink Summary
This chapter contains a summary on what you have learned in this tutorial and a recommendation on what subject you should study next.

XLink Reference
XLink attribute reference.

Multimedia Tutorial

2008-02-13T21:11:00.000-08:00

Multimedia Tutorial
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In this Multimedia tutorial you will learn how to add multimedia (sound and video) to your web pages.

Start learning Multimedia now!

Table of Contents

Introduction to Multimedia
This chapter describes what multimedia is and how multimedia can be handled by web browsers.

Sound Formats
This chapter describes the most common - or popular - sound formats.

Video Formats
This chapter describes the most common - or popular - video formats.

Browser Sounds
This chapter describes how to play sounds from a web page.

Browser Videos
This chapter describes how to play videos from a web page.

Windows Media Formats
This chapter describes the new Windows Media formats.

Object Intro
This chapter describes the object element.

Object QuickTime
This chapter describes how to play QuickTime movies with the object element.

Object RealMedia
This chapter describes how to play Real Audio and Real Video with the object element.

Tag Reference
The HTML multimedia tag reference.

Player Reference
The Windows Media Player reference.

SQL Tutorial

2008-01-22T02:04:00.000-08:00

SQL is a standard computer language for accessing and manipulating databases.

In this tutorial you will learn how to use SQL to access and manipulate data in Oracle, Sybase, SQL Server, DB2, Access, and other database systems.

Start learning SQL!

SQL Quiz Test

Test your SQL skills at W3Schools!

Start SQL quiz!
Exam - Get Your Diploma!

W3Schools' Online Certification Program is the perfect solution for busy professionals who need to balance work, family, and career building.

The ASP Developer Certificate is for developers who want to document their knowledge of ASP, SQL, and ADO.

JavaScript

2008-01-09T05:22:00.000-08:00

JavaScript Operators
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The operator = is used to assign values.

The operator + is used to add values.

The assignment operator = is used to assign values to JavaScript variables.

The arithmetic operator + is used to add values together.

y=5;
z=2;
x=y+z;

The value of x, after the execution of the statements above is 7.
JavaScript Arithmetic Operators

Arithmetic operators are used to perform arithmetic between variables and/or values.

Given that y=5, the table below explains the arithmetic operators:
Operator Description Example Result
+ Addition x=y+2 x=7
- Subtraction x=y-2 x=3
* Multiplication x=y*2 x=10
/ Division x=y/2 x=2.5
% Modulus (division remainder) x=y%2 x=1
++ Increment x=y++ x=6
-- Decrement x=y-- x=4

JavaScript Assignment Operators

Assignment operators are used to assign values to JavaScript variables.

Given that x=10 and y=5, the table below explains the assignment operators:
Operator Example Same As Result
= x=y x=5
+= x+=y x=x+y x=15
-= x-=y x=x-y x=5
*= x*=y x=x*y x=50
/= x/=y x=x/y x=2
%= x%=y x=x%y x=0

The + Operator Used on Strings

The + operator can also be used to add string variables or text values together.

To add two or more string variables together, use the + operator.

txt1="What a very";
txt2="nice day";
txt3=txt1+txt2;

After the execution of the statements above, the variable txt3 contains "What a verynice day".

To add a space between the two strings, insert a space into one of the strings:

txt1="What a very ";
txt2="nice day";
txt3=txt1+txt2;

or insert a space into the expression:

txt1="What a very";
txt2="nice day";
txt3=txt1+" "+txt2;The +

After the execution of the statements above, the variable txt3 contains:

"What a very nice day"
Adding Strings and Numbers

Look at these examples:

x=5+5;
document.write(x);

x="5"+"5";
document.write(x);

x=5+"5";
document.write(x);

x="5"+5;
document.write(x);

Try it yourself.

The rule is:

If you add a number and a string, the result will be a string.

Nanotechnology

2007-12-28T22:34:00.000-08:00

Abstract:
Marc Silverman is resigning as director of CTEK's Boulder Venture Center to start a new seed-stage funding group called Mountain Angel Capital, or MAC.

Silverman, a founder and former chief executive of Performance Health Technologies, took over the CTEK position in late May, replacing Jim Pollock, who left to head up a startup in Golden.

Mountain Angel Capital, Silverman said, primarily wants to invest in nanotechnology, software, clean tech and medical devices. It will announce relationships with a local venture capital company, an investment bank and a group of individual investors, all former CEOs who have run their own companies.

The new group plans to incorporate in January, and will make further announcements then.

XML Files

2007-12-14T03:43:00.000-08:00

Viewing XML Files

In Firefox and Internet Explorer:

Open the XML file (typically by clicking on a link) - The XML document will be displayed with color-coded root and child elements. A plus (+) or minus sign (-) to the left of the elements can be clicked to expand or collapse the element structure. To view the raw XML source (without the + and - signs), select "View Page Source" or "View Source" from the browser menu.

In Netscape 6:

Open the XML file, then right-click in XML file and select "View Page Source". The XML document will then be displayed with color-coded root and child elements.

In Opera 7 and 8:

In Opera 7: Open the XML file, then right-click in XML file and select "Frame" / "View Source". The XML document will be displayed as plain text. In Opera 8: Open the XML file, then right-click in XML file and select "Source". The XML document will be displayed as plain text.

Viewing XML Files

View a simple XML file (note.xml)
View the same XML file with an error
View an XML CD catalog
View an XML plant catalog
View an XML food menu

Viewing XML files with a dtd

View note.xml with an internal dtd
View note.xml with an external dtd

The Microsoft XML parser

View a simple XML file (xml_note.xml)
Loading the same file into the parser
Traversing the node tree of the file
Loading the same file into HTML

Displaying using JavaScript

View a simple XML file (xml_note.xml)
Format the same file with JavaScript

XML and CSS

View an XML CD catalog
View the corresponding CSS file
Display the CD catalog formatted with the CSS file

XML and XSL

View an XML food menu
View the corresponding XSL stylesheet
Display the food menu styled with the XSL stylesheet (IE6)
Display the food menu styled with the XSL stylesheet (IE5)

Data Binding

View an XML CD catalog
Bind the CD catalog to an HTML table
Add , , elements

Database Output

View XML output from a database

Displayed as HTML

View an XML CD catalog
See how the CD catalog can be displayed inside HTML elements
See how the CD catalog can be displayed inside an HTML table
See how to navigate the CD catalog
A simple CD catalog application

Requesting XML data from a server

Send a request to the server
Communicating with a server using XML

Using the XMLHttpRequest Object

Load an XML file with XML HTTP (JavaScript)
Load an XML file with XML HTTP (VBScript)
Load a textfile into a div element with XML HTTP (JavaScript)
Make a HEAD request with XML HTTP (JavaScript)
Make a specified HEAD request with XML HTTP (JavaScript)

XML Behaviors

XML Behaviors

Web design

2007-12-09T02:48:00.000-08:00

Users Are Scanners

If you think a typical user will read the entire content of your Web pages, you are wrong.

No matter how much useful information you put into a Web page, a visitor will only spend a few seconds scanning it before they decide whether to leave it or to stay.

If you want a visitor to read your text, be sure to make your point in the very first sentence of the page. After that you should try to keep them occupied with short paragraphs and interesting new headers all the way down the page.
Less Is More

Try to keep all sentences as short as possible. Try to keep your paragraphs as short as possible. Try to keep your chapters as short as possible. Try to keep your pages as short as possible.

Use a lot of space between your paragraphs and chapters. Pages overloaded with text will kill your audience.

Don't place too much content on a single page. If you have a lot to say, try to break your information into smaller chunks and place it on different pages. Don't expect any visitor to scroll all the way down to the bottom of a page with thousands of words.
Navigation

Try to create a navigation structure that is common for all the pages in your Web.

Keep the use of hyperlinks inside your text paragraphs to a minimum. Don't use hyperlinks inside text paragraphs to send your visitors to every random page of your Web. That will destroy the feeling of a consistent navigation structure.

If you must use hyperlinks, add them to the bottom of a paragraph or to the navigation menus of your site.
Download Speed

A common mistake made by many web designers is to develop a site on a local machine with direct access to the data, or to develop the site over a high-speed Internet connection. Sometimes developers are not aware of the fact that some of their pages take a long time to download.

Internet usability studies tell us that most visitors will leave a Web page that takes more than 7 seconds to download.

Before you publish any content heavy pages, make sure they are tested over a low-speed modem connection. If your pages take a long time to download, you might consider removing some of your graphic or multimedia content.
Let Your Audience Speak!

Feedback from your users is a very good thing. Your visitors are your "customers". Very often they will give you some valuable wisdom, or advise you, completely free of charge, about what you could have done better.

If you provide a simple way to reach you, you will get a lot of positive input from a lot of people with different skills and knowledge.

JavaScript

2007-12-04T01:09:00.000-08:00

JavaScript is used in millions of Web pages to improve the design, validate forms, detect browsers, create cookies, and much more.

JavaScript is the most popular scripting language on the internet, and works in all major browsers, such as Internet Explorer, Mozilla, Firefox, Netscape, and Opera.
What You Should Already Know

Before you continue you should have a basic understanding of the following:

* HTML / XHTML

If you want to study these subjects first, find the tutorials on our Home page.
What is JavaScript?

* JavaScript was designed to add interactivity to HTML pages
* JavaScript is a scripting language
* A scripting language is a lightweight programming language
* A JavaScript consists of lines of executable computer code
* A JavaScript is usually embedded directly into HTML pages
* JavaScript is an interpreted language (means that scripts execute without preliminary compilation)
* Everyone can use JavaScript without purchasing a license

Are Java and JavaScript the Same?

NO!

Java and JavaScript are two completely different languages in both concept and design!

Java (developed by Sun Microsystems) is a powerful and much more complex programming language - in the same category as C and C++.
What can a JavaScript Do?

* JavaScript gives HTML designers a programming tool - HTML authors are normally not programmers, but JavaScript is a scripting language with a very simple syntax! Almost anyone can put small "snippets" of code into their HTML pages
* JavaScript can put dynamic text into an HTML page - A JavaScript statement like this: document.write("

" + name + "

") can write a variable text into an HTML page
* JavaScript can react to events - A JavaScript can be set to execute when something happens, like when a page has finished loading or when a user clicks on an HTML element
* JavaScript can read and write HTML elements - A JavaScript can read and change the content of an HTML element
* JavaScript can be used to validate data - A JavaScript can be used to validate form data before it is submitted to a server. This saves the server from extra processing
* JavaScript can be used to detect the visitor's browser - A JavaScript can be used to detect the visitor's browser, and - depending on the browser - load another page specifically designed for that browser
* JavaScript can be used to create cookies - A JavaScript can be used to store and retrieve information on the visitor's computer