Java Applet Java Applet runs inside a Java plugin in the explorer. In IE, the plugin is a kind of ActiveX. Please see the diagram.
Hoever, in firefox, it is a plugin implemented byGecko SDK(npapi), please see,

Strong Points Across the platform, the applet can be explained in IE and Firefox, Windows and Linux/Unix. Shortcoming

Not each user has the JRE installed. Flash Flash is like applet, it is also an ActiveX plugin in IE and Gecko SDK in Firefox. But it should be more related to Multi-Media(HTTP GET and POST is also used inside flash) while Applet has more API available to do anyting. Please see the diagrams in IE and firefox.



Strong Points Across the platform, theflash can beplayed in IE and Firefox, Windows and Linux/Unix. There is no enough API do some rich operasions compared to Appllet(java)? Shortcoming Not each user has theFlash Player Plugininstalled. ActiveX/Gecko SDK Plugin They are the real explorer plugins. Actually, the JRE plugin and Flash Player Plugin are also kind of ActiveX or Gecko SDK Plugin themself. They explain the Applet or the Flash. IE/Firefox ------>>ActiveX/Gecko SDK Plugin IE/Firefox ------>> JRE plugin ------>> Appllet IE/Firefox ------>>Flash Player Plugin ------>> Flash Strong Points

More flesiblesince they are the real pluginprogrammed by C++both in IE and Firefox usually. Shortcoming You need to implement different for IE and Firefox. For IE, you need use Windows/COM API. For Firefox, you need use the Gecko SDK/npapi.