This is a natural consequence of the fact that each applet appears within a browser window. In addition to its graphical UI, an applet can use several other UI types, depending on the kind of information it needs to give or get.
Some applets play sounds, either to give the user feedback or to provide ambiance.
Applets can get configuration information from the user through parameters that the applet defines. For information about sound, parameters, and status strings, see Taking Advantage of the Applet API .