# What is a plug-in?

**URL:** <https://boards.straightdope.com/t/what-is-a-plug-in/166788>\
**Category:** Factual Questions\
**Created:** [April 6, 2003, 2:04am UTC](https://boards.straightdope.com/t/what-is-a-plug-in/166788 "2003-04-06T02:04:33Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![quasar](https://avatars.discourse-cdn.com/v4/letter/q/48db29/32.png) [@quasar](https://boards.straightdope.com/u/quasar)\
**Post date:** [April 6, 2003, 2:04am UTC](https://boards.straightdope.com/t/what-is-a-plug-in/166788/1 "2003-04-06T02:04:33Z")

</div>

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

---

<div class="post-metadata">

**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\
**Post date:** [April 6, 2003, 2:08am UTC](https://boards.straightdope.com/t/what-is-a-plug-in/166788/2 "2003-04-06T02:08:35Z")

</div>

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.

---

<div class="post-metadata">

**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\
**Post date:** [April 6, 2003, 2:17am UTC](https://boards.straightdope.com/t/what-is-a-plug-in/166788/3 "2003-04-06T02:17:52Z")

</div>

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.

---

<div class="post-metadata">

**Author:** ![AHunter3](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ahunter3/32/368_2.png) [@AHunter3](https://boards.straightdope.com/u/AHunter3)\
**Post date:** [April 6, 2003, 2:32am UTC](https://boards.straightdope.com/t/what-is-a-plug-in/166788/4 "2003-04-06T02:32:24Z")

</div>

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.

---

<div class="post-metadata">

**Author:** ![quasar](https://avatars.discourse-cdn.com/v4/letter/q/48db29/32.png) [@quasar](https://boards.straightdope.com/u/quasar)\
**Post date:** [April 6, 2003, 5:08pm UTC](https://boards.straightdope.com/t/what-is-a-plug-in/166788/5 "2003-04-06T17:08:56Z")

</div>

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