Java is an object-oriented, programming language developed by Sun Microsystems, who are noted for their Unix workstations. The Java language is designed to be small, simple and portable across platforms and operating systems, both at the source and at the binary level. Sun also created HotJava as a browser to run Java programs called applets.
Applets are programs that are interactive and dynamic and run inside a Web page.
They create the animation, figures, games, and allows response to input from readers, etc. Applets are written and compiled using Java. You can make applets available just like HTML files, but your browser must be Java-capable to run the applet, which most browsers are. If your browser is not Java-capable, you will either see text, a static graphic or nothing. It is also an object-oriented language, which allows you to create flexible, modular programs and even reuse the code.