Microsoft Defender Antivirus

Updated: 05/02/2021 by Computer Hope
Microsoft Defender

Microsoft Defender Antivirus is antivirus software developed by Microsoft to protect computers running Windows. It 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 first released on October 24, 2006.

Windows Defender

Microsoft Defender is installed by default on Windows 10.

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?

Once installed, 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 Search programs and files box, type antivirus or microsoft defender.
Note

In Windows 8, type microsoft defender on the Start screen.

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

If you have another antivirus program installed on your computer, like AVG, McAfee, or Webroot, Microsoft Defender is disabled to prevent conflicts with the antivirus program.

How do I enable or disable Microsoft Defender?

After installing Microsoft Defender, or if Microsoft Defender is preloaded in Windows (e.g., Windows 8 and Windows 10), it is automatically enabled.

To disable it, follow the steps below.

  1. Open Microsoft Defender.
  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.

To enable Microsoft Defender, try the steps below.

  1. Open Microsoft Defender.
  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 is now enabled.
  3. If no link is available in the pop-up message, you need to 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 shown. Select Microsoft Defender in the list and click the Turn on button.
Note

If other antivirus or antispyware programs are installed and running on your computer, you may not be able to enable Microsoft Defender. Many antivirus and antispyware programs do not run properly if Microsoft Defender is also enabled. The Turn on button may be greyed out in that case and you cannot enable Microsoft Defender.

Security terms