What is a plug-in?

I keep hearing it mentioned, yet still don’t know what it is. Would a gentle soul be willing to eradicate some of my computer illiteracy?

Thanks,

quasar

A plugin is a file that adds additional, optional functionality to a program. For instance, for MS Word, you can get plugins that will let you spell check a foreign language.

A plugin is a program that does a specific task for another program. Plugins generally depend on the `host’ program for most basic functions, and can only work if used in conjunction with the larger program.

Exactly. Many commercial software products have a published Application Programming Interface (API), a set of routines and instructions that 3rd party software can use to modify the way the commercial software behaves. This improves the reach and usefulness of the commercial product, which benefits the software company responsible for it, while also bringing revenue to the authors of the plug-ins.

Some famous plug-ins are Kai’s Power Tools for Photoshop; and the Macromedia Flash plug-in for Netscape, Internet Explorer, and other browsers.

Clear enough. Thanks for the nice explanations, Q.E.D, Derleth and AHunter3.