Why won't Java applets run in my Web browser?
Answer: Java applets are small programs that are typically designed to run in a Web browser. Common applets include math programs, 3D model viewers, and various types of games. Since these programs are written in Java, they require a Java compiler, or Java Virtual Machine (JVM) to run.
Most computer systems today come with Java pre-installed, which includes support for Java applets. However, some applets may contain code that requires an updated version of Java. This means they won't run on computers with older Java installations. Also, if Java is not installed correctly, some Web browsers may not recognize Java applets.
The remedy for both of these problems is to install the latest version of Java. Fortunately, Java is available as a free download. Windows and Linux users can get the latest version of Java at Sun Microsystems' Java Downloads page. Since Java is installed as part of Mac OS X, Mac users can update their Java installation using the Mac OS X "Software Update" feature.
After installing the latest version of Java, you may be asked to restart your computer. Once your computer restarts, open your Web browser and try loading the Java applet that wouldn't open before. It should be recognized by your browser and will run using the newly installed Java Virtual Machine.