Java and JavaScript extend the capabilities of web pages on-the-fly. Web pages consist of more than text and graphics — they also often contain little programs that scroll text, display graphics, calculate results, and perform other actions. These programs are sometimes called “applets” as a diminutive of “applications”. The most common applets are Java programs and JavaScript / ECMAScript scripts.
These applets are written in compact, text-based computer languages, so they take up little bandwidth and are downloaded very quickly, making them ideal for adding sophisticated custom functionality to a web page that may be accessed over low bandwidth connections.
JavaScript programs are usually embedded in the page when it is downloaded from the Internet. This site LivingInternet.com is run by JavaScript programs — you can view some of the code by selecting “View / Source” from your browser menu. Java programs may be downloaded with a web page, or downloaded quickly when the user performs an action that specifically requires it.
Applets run on a software engine in your web browser or on your computer called a “virtual machine”. Most web browsers include a virtual machine for JavaScript, and most operating systems include a virtual machine for Java.
You can sometimes tell when an applet is running when a message is displayed in the browser border saying something like: “Applet ThisApplet running”.
Resources. The official Sun Java site provides the central resource for information on Java.
The following sites provide more information on JavaScript: