Windows Defender

Updated: 01/31/2019 by Computer Hope

Originally known as Microsoft AntiSpyware, Windows Defender is a free protection program provided by Microsoft to help protect computers running Windows from spyware and malware. With the introduction of Windows 8, Microsoft added improved functionality to Windows Defender by adding antivirus protection, as well as spyware and other malware protection.

Windows Defender

Windows Defender is based on GIANT AntiSpyware from the GIANT Company Software, Inc. company that Microsoft acquired on December 16, 2004. It was first released to the public on October 24, 2006, and is available as a free download for Microsoft Windows 2000, XP, Vista, and 7. Windows 8 and 10 computers already have this program installed and active unless other antivirus programs are installed.

How do I open Windows Defender?

Once installed, Windows Defender will automatically start and run each time your computer starts up, unless some other program has disabled it. If you want to open Windows Defender, follow the steps below.

  1. Click the Start button.
  2. In the Search programs and files box, type windows defender.
  3. In the search results, click on Windows Defender. You may need to press the Enter key to open the program.

Note: In Windows 8, start typing windows defender on the Start screen and select Windows Defender in the search results.

Note: In Windows 10, type windows defender in the search box on the Taskbar, next to the Start button, and select Windows Defender in the search results.

How do I enable or disable Windows Defender?

After installing Windows Defender, or if Windows 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 Windows Defender.
  2. Click the Tools option in the top menu.
  3. On the Tools and Settings screen, click on Options.
  4. On the Options screen, in the left navigation pane, click on Administrator.
  5. Uncheck the box for Use this program.

To enable Windows Defender, try the steps below.

  1. Open Windows Defender.
  2. You should see a pop-up message stating the program is turned off. If available, click on the click here to turn it on link in that pop-up message. Windows 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 on the Security option to expand that section.
  5. Click on either the View installed antivirus apps or View installed antispyware apps option.
  6. A list of installed antivirus or antispyware programs is shown. Select Windows 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 Windows Defender. Many antivirus and antispyware programs do not run properly if Windows Defender is also enabled. The Turn on button may be greyed out in that case and you will not be able to enable Windows Defender on.

Security terms