Browser Extension

A browser extension is a small software add-on that adds new functionality to a web browser. It may change how a built-in feature works or add new features entirely. For example, an extension may add a way to translate selected text or change how tabs appear when a browser is used full-screen. Extensions can also integrate website features directly into the browser, like tweeting a link to the current webpage, or saving an image to a Pinterest board.

Many browsers have a central repository of extensions where you can browse and install extensions, like the Chrome Web Store or the Safari Extensions section of Apple's App Store. These central locations sort extensions into several categories and provide descriptions, screenshots, and user reviews for each one.

You can install extensions directly from a developer's website, but remember to pay close attention to what data the extension will access. An extension from a disreputable developer could turn out to be malware that steals passwords or secretly redirects your traffic.

After installing an extension, an icon for it will usually appear on the browser's toolbar. Clicking the icon will open a menu where you can invoke the extension or customize its settings. A browser that supports extensions will also provide a way to manage them, such as enabling or disabling them at any time, or removing ones that are no longer needed.

NOTE: Browser extensions are each written for a specific browser, so one designed for Safari won't be compatible with Firefox or Chrome. However, two browsers that share an underlying browser engine (like the Chromium engine that powers both Google Chrome and Microsoft Edge) can share extensions.

Updated September 21, 2022 by Brian P.
Reviewed by Per C.

quizTest Your Knowledge

What term is synonymous with desktop background?

Screen saver
Operating system
Correct! Incorrect!     View the Wallpaper definition.
More Quizzes →

The Tech Terms Computer Dictionary

The definition of Browser Extension on this page is an original definition written by the team. If you would like to reference this page or cite this definition, please use the green citation links above.

The goal of is to explain computer terminology in a way that is easy to understand. We strive for simplicity and accuracy with every definition we publish. If you have feedback about this definition or would like to suggest a new technical term, please contact us.

Sign up for the free TechTerms Newsletter

How often would you like to receive an email?

You can unsubscribe or change your frequency setting at any time using the links available in each email.

Questions? Please contact us.