Microsoft Defender Antivirus

Microsoft Defender Antivirus is antivirus software developed by Microsoft to protect computers running Windows. It scans, detects, and removes viruses, spyware, and malware, helping to protect the operating system from infection.

Formerly known as Microsoft AntiSpyware and Windows Defender, the software was originally based on GIANT AntiSpyware, acquired by Microsoft on December 16, 2004. It was released on October 24, 2006.

There is no need to download and install Microsoft Defender Antivirus, as it is installed by default on Windows 8, Windows 10, and Windows 11. It is also available with Windows Vista and Windows 7, but only protects against spyware.

Does Microsoft charge for Microsoft Defender Antivirus?

No. The latest versions of Microsoft Windows come with Microsoft Defender for free.

How do I open Microsoft Defender Antivirus?

Microsoft Defender automatically starts and runs each time your computer starts up, unless it is disabled.

To open Microsoft Defender manually, follow the steps below.

1. Click Start or press the Windows key.
2. In the Windows search box, type antivirus or microsoft defender.

3. In the search results, click Microsoft Defender or Virus & threat protection. You may need to press Enter to open the program.

How do I enable or disable Microsoft Defender Antivirus?

Microsoft Defender Antivirus is enabled by default, so there is no need to manually enable it unless it was previously disabled.

Disable Microsoft Defender Antivirus

1. Open Microsoft Defender Antivirus.
2. Click the Tools option in the top menu.
3. On the Tools and Settings screen, click Options.
4. On the Options screen, in the left navigation pane, click Administrator.
5. Uncheck the box for Use this program.

Enable Microsoft Defender Antivirus

1. Open Microsoft Defender Antivirus.
2. You should see a pop-up message stating the program is turned off. If available, click the click here to turn it on link in that pop-up message. Microsoft Defender Antivirus is now enabled.
3. If a link is not available in the pop-up message, you must open the Control Panel and access the Security and Maintenance option.
4. In the Security and Maintenance window, click the Security option to expand that section.
5. Click the View installed antivirus apps or View installed antispyware apps option.
6. A list of installed antivirus or antispyware programs is displayed. Select Microsoft Defender Antivirus in the list and click the Turn on button.

Security terms