Security and Restriction:

To actually understand the Java security model-why it's significant, how it works, and how to work with it-you should have a good idea about the kinds of security attacks which are possible and that system resources could be used to mount such attacks. It takes care to protect these resources from untrusted code. That permits you to configure applet security If you are using a Java application or if you are writing a Java application which loads classes from the Net, it helps to understand only what doors you may be opening when you provide an applet access to a particular resource.