plug History

Plug-ins appeared as early as the mid 1970s, when the EDT text editor running on the Unisys VS/9 operating system using the Univac 90/60 series mainframe computer provided the ability to run a program from the editor and to allow such a program to access the editor buffer, thus allowing an external program to access an edit session in memory. The plug-in program could make calls to the editor to have it perform text-editing services upon the buffer that the editor shared with the plug-in. The Waterloo Fortran compiler used this feature to allow interactive compilation of Fortran programs edited by EDT.
Very early PC software applications to incorporate plug-in functionality included HyperCard and QuarkXPress on the Macintosh, both released in 1987. In 1988, Silicon Beach Software included plug-in functionality in Digital Darkroom and SuperPaint, and Ed Bomke coined the term plug-in.
Currently^[update], programmers typically implement plug-in functionality using shared libraries compulsorily installed in a place prescribed by the host application. HyperCard supported a similar facility, but more commonly included the plug-in code in the HyperCard documents (called stacks) themselves. Thus the HyperCard stack became a self-contained application in its own right, distributable as a single entity that end-users could run without the need for additional installation-steps.
Firefox also supports plug-ins using NPAPI. When the browser encounters references to content a plug-in specializes in, the data is handed off to be processed by that plug-in. Since there is generally a clear separation between the browser and the plug-in, the results are discrete objects embedded within a webpage. The same distinction between plug-ins and extensions is in use by other web browsers, such as Microsoft Internet Explorer, where a typical extension might be a new toolbar, and a plug-in might embed a video player on the page. Since plug-ins and extensions both increase the utility of the original application, Mozilla uses the term "add-on" as an inclusive category of augmentation modules that consists of plug-ins, themes, and search engines...concats 00923224479031