These technologies are built into the system of Internet servers, applications, and content and are transparent to users. JavaScript works largely as an extension of the Internet's standard HTML language. Whereas plug-ins are tailored for a particular computer system, Java programs operate across the network, regardless of platform. Because Java capabilities are built into Communicator, Java applets require no installation.
Users can disable language technologies in the Advanced preferences panel.
You can learn about JavaScript and Java through Netscape's Communicator Web pages and retail textbooks.