Every applet can run in multiple threads.
But no application ever calls them from the AWT drawing and event handling thread. Many browsers, such as Netscape Navigator 2.0 for Solaris, allocate a thread for each applet on a page, using that thread for all calls to the applet's major milestone methods. Some browsers allocate a thread group for each applet, so that it's easy to kill all the threads that belong to a particular applet. In any case, you're guaranteed that every thread that any of an applet's major milestone methods creates belongs to the same thread group. Below are two PrintThread applets.