JavaScripts are often used for site hit counters, live clocks, form input delivered by e-mail, interactive games, mouseovers, and calculations. Unfortunately, not all browsers consistently support Java and its related applications. If you experience a lot of JavaScript errors, your best bet is to upgrade your browser or switch from MS IE to Netscape. Java Applications require programming knowledge to create and stand alone as independent programs. They rely on other files to function properly and require some programming knowledge to create.
Applets add interactivity to a Web site.
JavaScripts are also imbedded in HTML, but they are executed by the Web browser. They do not rely on other files to function. Scripts can often be found for free on the Internet, and they can be created without programming knowledge. JavaScripts also add interactivity to a Web site.