JavaScript was developed by Netscape Communications Corporation, the maker of the Netscape web browser. JavaScript was the first web scripting language to be supported by browsers, and it is still by far the most popular.

JavaScript is almost as easy to learn as HTML, and it can be included directly in HTML documents. Here are a few of the things you can do with JavaScript:

• Display messages to the user as part of a web page, in the browser's status line, or in alert boxes

• Validate the contents of a form and make calculations (for example, an order form can automatically display a running total as you enter item quantities)

• Animate images or create images that change when you move the mouse over them

• Create ad banners that interact with the user, rather than simply displaying a graphic

• Detect the browser in use or its features and perform advanced functions only on browsers that support them

• Detect installed plug-ins and notify the user if a plug-in is required

• Modify all or part of a web page without requiring the user to reload it

• Display or interact with data retrieved from a remote server