If an Applet sends data to the System output stream, this will not appear in the Applet's window. Netscape has a "Java Console" that will show this output. Using the Applet viewer, this output will appear in the command window that the viewer was started from.

Applets can not access local files at all.

Applets can only talk across the network to the host machine that they were loaded from.

Parameters for Applets are specified in the HTML, and are read by making calls to various Applet class methods, e.g. getParameter().