An applet is a bean that is designed to be run inside a Web browser and that inherits from java.applet.Applet or javax.swing.JApplet .
The Eclipse-based launcher has its own applet stub that is used to run the applet. This stub automatically starts the applet after it has been instantiated by calling its start() method. Unlike the JRE applet launcher, which the Java bean launcher does not use, the stub does not check authority profiles to see whether the applet can perform tasks such as input/output or opening sockets. This means you can quickly test your applet's run-time appearance and behavior without worrying about security certificates.
To test an applet in the Java bean launcher:
When you have finished testing your applet and are ready to deploy it in a browser, you can use the simple HTML <applet> tag as long as the class does not require any JDK 1.2 or higher features, such as any of the Swing classes. If your applet uses any JDK 1.2 or higher features, then the HTML syntax to embed it into a page is more complex. This is required in order to deal with differences between browsers, and to ensure that the applet uses the correct Java plug-in. For more information about applets and Java plug-ins, refer to http://www.java.sun.com.
Related concepts
Visual Editor for Java
Related tasks
Composing classes visually
Testing a Java bean
Related information
http://www.java.sun.com.