applet

A small application. Usually used in reference to a Java program loaded inline with a web page.

Applets are another example of a great idea, poorly implemented. While it's getting better, but there are still a few common problems associated with applets. Browser incompatabilities, differences in JREs, as well as the extra bandwidth and client-side muscle which it takes to run them.

Overall, I am not opposed in applets in web-design -- however, you pretty much always have to have backups for the places where Java isn't practical. Or risk alienating people on slow modem connections, Linux/Opera/Netscape 2.0 users, or anyone who turns their Java off.

A Java object used to set small applications inside web pages. The Applet class extends Panel, that extends Container, a sub class of Component. This means you have all the standered component methods.
Web browsers basically interface with applets through the methods init, start, paint, stop and destroy.

An applet actually specifies any small computer program designed to work with a very specific user interface. Usually this interface involves a display (plain canvas or more advanced windowing toolkit) and method of user input (mouse clicks, menus, keyboard, etc.) The point being, of course, is to use that specific interface to integrate applets into a larger program. Java applets work with standard Java UI components, like AWT or Swing, to integrate with your web browser.

Other examples of applets include Gnome applets, WindowMaker (GnuStep) dockapps, some Winamp plugins, even the system tray items in Windows. Of these, only WM dockapps are capable of running while not nested in their native program.

While it's expected that an applet will be a thin program, there are generally no real-life limitations on applet size (actually, Java puts a limit on the heap size for applets, but this goes for all Java programs, not just applets) or system priority. Some applet interfaces limit what kinds of actions the applet can perform; for example, Java applets (unless they go through a trust-gaining mechanism) can't make new IP sockets or open files, for obvious security reasons. Gnome and WM dockapps do not have such limitations, since they aren't automatically downloaded and executed by browsers.