What Is A Browser Extension?

Date First Published: 12th December 2023

Topic: Computer Systems

Subtopic: Computer Software

Article Type: Computer Terms & Definitions

Difficulty Level: 4/10

Learn about what a browser extension is in this article.

A browser extension is a small add-on that adds extra functionality or capabilities to a web browser. Extensions are usually used to add new features, enhance the functionality and appearance of a web browser, manage cookies, remove unwanted popups and ads, and improve security. For example, Adblock is a popular web browser extension used to block ads from appearing on webpages and filter content.

After installing an extension, an icon for it will usually appear in the browser toolbar. Clicking on the icon will open a menu where its settings can be customised. A browser that supports extensions will also come with a way to manage them, such as enabling, disabling, or removing them. Browser extensions are not compatible with other web browsers because they are written for a specific browser, but if the web browsers share a browser engine (e.g. Chromium that powers both Google Chrome and Microsoft Edge), they can share extensions.

Best Practices For Extensions

Best practices for extensions are:

• Stick with extensions from official sources - It is always best to install extensions from official sources, like the Chrome Web Store or the Safari Extensions section of Apple's App Store. An extension from an unreputable source could contain hidden malware that logs keystrokes or steals sensitive information, like passwords. There are other places to download extensions, including the developer's website, but official sources should be the first place you look.
• Research before installing - Before choosing an extension, always ensure that it is suitable for the tasks you want to perform with it. Extensions won't be useful if they don't add any value. Also, consider whether the extension has a privacy policy, the permissions it has in your web browser, and the reviews.
• Don't overload your browser with extensions - The more extensions you install, the slower your web browser will run. Overloading your web browser with extensions can make it run slower and even freeze or crash it. Before installing a plugin, always consider whether you really need the plugin. You may already have a feature that is capable of doing what you want to.
• Keep the extensions up to date - Updates can fix security vulnerabilities and bugs discovered by other users. Outdated extensions can be a threat to security, so ensure that you are keeping them up to date.
• Remove unused extensions - If you have an extension that you no longer use, it is probably not worth keeping it on your web browser. Uninstalling it will free up space for other extensions and speed up your web browser. If you are not sure how an extension got installed or where you got it from, then it is best to remove it.

Security Risks Of Browser Extensions

Browser extensions come with some security risks. Like other types of software, extensions can be programmed to perform malicious tasks or undesirable behaviours, like stealing passwords, secretly monitoring browsing history, or making unauthorised changes to browser settings, due to the broad permissions they have over the web browser.

Legitimate extensions can also be faked, leading to versions that contain malware and expose users and their data to major privacy and security risks. That is why it is recommended to only download browser extensions from reputable sources, like the Chrome Web Store or the Safari Extensions section of Apple's App Store.

Difference Between Browser Plugins and Browser Extensions

Browser plugins are different to browser extensions and are no longer supported by the major browsers. One difference between plugins and extensions is that extensions are distributed as source code, whilst plugins are executables. Google Chrome has over 150,000 extensions available in the Chrome Web Store, but stopped supporting plugins in 2020.

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