JavaScript

JavaScript is a relatively easy-to-learn computer scripting language that allows people who already know HTML to add interactive elements to their websites. Like Applets, JavaScript is embedded in the HTML document. JavaScript functions don't run on a web server computer, but on an individual Internet user's computer. Like other programs written in scripting languages, JavaScript functions aren't as quick as programs written in true programming languages like Java but they are easier to create and are frequently used for small applications.

Will JavaScript functions make your website SEO-friendly? Not likely. It won't hurt, but JavaScript functions will be virtually invisible to search engines. Like graphics and similar dynamic content, JavaScript isn't indexed by search engines because a search engine can't see JavaScript functions on the web page. Therefore, JavaScripts won't affect PageRank and should not be a substitution for written "search engine friendly" content.

Brendan Eic developed JavaScript for Netscape Navigator web browser. JavaScript was primarily intended for web authors (non-programmers) who are used to creating websites in HTML, but who aren't familiar with complex computer languages such as C++ or Java (which is an unrelated computer programming language that is also frequently used for client-side applications on the Internet).

JavaScript allows web authors to add interactive features like making dynamic slide shows that scroll, rewind, and pause. JavaScript functions are also helpful in creating pop ups, validating forms filled out online, creating calculators, sniffing for plug-ins, and creating roll-overs (when a picture or words change when you roll over it with a mouse). It's also helpful for reporting webpage statistics and doing client-side processing.

JavaScript is supported by several big names in the computer industry, including Microsoft and Netscape. It is an open source language, which means that you don't need a license to author JavaScript.

It is important to remember that, technically, JavaScript is a scripting language, not a computer programming language like Java or a markup language like HTML. JavaScript is now one of the most often used languages on the world wide web.