Plugin

A plugin (or plug-in) is a (small) computer program that can be connected to another (larger) program to execute a certain, usually very specific, function. Typical examples are plugins to display specific graphic formats (e.g., SVG), to play multimedia files, to encrypt/decrypt email (e.g., PGP), or to filter images in graphic programs. The main program (a web browser, an email program, etc.) sets a standard for the data exchange with a plugin, transmits the data to process to the plugin and gets back the results.