What is a Java Applet?

A Java applet is a small application written in the Java programming language.

In most cases, Java applets are used on Web sites as sophisticated navigation menus, miniature Web puzzles, etc. When your browser sees an applet it downloads it and runs it on your computer. This is the default or "factory" configuration of most browsers. However, there is a danger that a Java applet could mask a Trojan horse or similar program, which may sneak onto your computer. Therefore Web browsers should be configured to run Java applets only after asking you each time. Java applets should be only be allowed to run when they are from sites you know are reliable.