What is a Browser or Computer Plug-in, Add-on, or Extension?

A plug-in, add-on, or extension are generally the same thing; a software component that adds a feature to an existing computer program. This can be part of a stand-alone app or part of an internet browser. For example, a browser plug-in expands a web browser's functionality by installing specific toolbars, adding buttons, links, or other useful functions, like pop-up blocking.

What do plug-ins do?

Applications and browsers support plug-ins, add-ons, and extensions for multiple reasons: to allow third-party developers to create specific functions, to add new features easily, and to expand functionality.

Legitimate application plug-ins include add-ons that can encrypt and decrypt email, emulate video game consoles, process and analyze sound, and provide text editors. Legitimate browser plug-ins include search toolbars, media players, and text readers.

These plug-ins can be very useful and when developed by an authorized company, safe and harmless to download.

An illustration of browser extensions in a browser window

What about malicious add-ons?

Some plug-ins, add-ons, or extensions are malicious, however, and can install adware, install spyware, or redirect your browser to a specific site. These plug-ins are often installed without explicit user consent and frequently have no easily-accessible way to uninstall them.

Malicious extensions can be installed if you click on an unknown dialog box or an ad that goes to a questionable site. Most modern operating systems have an automatic verification to ensure you want to download new software. If this verification question comes up when you're not actively trying to download something, click No.

Close up of a computer screen whereby a mouse pointer is closing a suspicious pop-up window

How to remove an extension?

Legitimate plug-ins, add-ons, and extensions can be removed using the "Uninstall" function in your operating system.

For computers running Microsoft Windows:

Windows 10

  1. Select the gear icon, then Settings
  2. Select System, then Apps & features
  3. Click on the progam you want to remove, an Uninstall button will appear.

Windows 8 and earlier

  1. Click Start or the Windows icon, then select Control Panel
  2. Select Uninstall a program, then select the program you want to remove.
  3. Click Uninstall, then answer the prompts.

Malicious plug-ins, add-ons, and extensions require more work to remove. Even if the malicious software is listed in the program list (it rarely is), you cannot trust that using the operating system to uninstall it will remove all portions of the program. The easiest and best way is to run anti-malware software. When the software finds a malicious program, use the anti-malware program to remove the malicious program. Learn more about anti-malware software. 

There are also specific malware removal tools. Choose one that is produced by your operating system developer or by a reputable anti-virus software company.

Plug-ins, add-ons, and extensions can expand the capabilities of your browser or applications. Be sure you get all software from a reputable company to avoid malware.

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