There are 2 plugin architectures supported by the WebKit framework: "Netscape" plugins and "WebKit" plugins.
"Netscape" plugins (.plugin) conform to the Netscape plugin API which is a C API that designates the required functions that the plugin must support and the functions that the browser will provide. For more information, see
http://www.mozilla.org/projects/plugins/.
"WebKit" plugins (.webplugin) are a new Objective-C based plugin API that Apple developed specifically for use in Safari and other WebKit based applications. For more information see
http://developer.apple.com/documenta...itPlugins.html.