Windows 10 (and the older 8.1) includes an antivirus tool called Windows Defender. This protects you against viruses and scans for malware on your PC.
This official protection should be turned on when you buy a new computer or install Windows 10 for the first time, although it will deactivate itself if you install another antivirus package.
Want to see how Windows 10 Defender compares to Norton, Kaspersky and McAfee? Read our Which? reviews of the best antivirus software.
Run a basic scan with Defender
Click on the Start button in the bottom left of Windows 10 and then click on All Apps, then Windows System and Windows Defender, or type Defender into the search panel and select Windows Defender to bring up the software’s control panel.
You can choose to run a Quick Scan or Full Scan from the options on the right-side of the home page.
A quick scan examines only the drives and folders most likely to contain bugs, while a full scan can take a long time, but will look in every nook and cranny or your PC for malware.
Custom scans with Windows Defender
If you have an external hard drive that you only plug in occasionally, or if someone gives you a USB thumb drive with music or video onboard, it’s worth doing a check for viruses before you open the USB drive.
Plug the device into your PC, then, from the Home tab of Windows Defender, tick the Custom option on the right-hand side, then hit the Scan Now button. This brings up a list of available drives – select the one you’ve plugged in and click OK to check that particular location for any signs of malware.
Check Windows Defender scan results
When Windows Defender finds a virus or potentially unwanted item, it puts it into quarantine, where it cannot run unless you give it express permission.
You can examine whatever nasties Defender has found by clicking on the History tab and then the Quarantined items. Click the View details button to bring up a list of the threats – you may need to input an administrator password at this stage.
You can review each item by highlighting it, and Defender gives a threat-level warning to help you decide whether the file is really a danger. Check the box next to each threat, then hit Remove to clean the software from your PC or Restore if you trust the software. Microsoft warns against restoring anything that’s given a Severe or High threat rating.