Part of JDK
that is used to view Java applet
s. This utility
reads a HTML
file and parses each <APPLET ...> ... </APPLET> it encounters. (New version may - or may not - support the newer, recommended <OBJECT> tag.)
It can also be used to show stuff that the web browsers don't show yet, like the applet information and parameter details (if the applet provides them).
In reality, it's often seen that what starts in appletviewer may end up not working in the web browser (mostly because appletviewers often support newer version of Java API than browsers).