Windows Defender and Windows SmartScreen are built into Windows 8 and Windows RT and help guard your PC against viruses, spyware, and other malicious software in real time. Windows Defender uses green, yellow, and red color codes to show your PC’s security status.
If there’s a red or yellow threat, Windows Defender notifies you and recommends what to do.
When Windows Defender detects a suspicious app or other unfamiliar software, it checks it against a Microsoft database to make sure it isn’t known to do anything potentially harmful. Windows Defender keeps track of known malware automatically, but you can also get updated lists whenever you want.
These definitions are updated automatically, and whenever you tap or click Update.
Windows Defender runs in the background, and only notifies you if there are specific actions to take—but you can also run your own scan whenever you want. If your PC isn’t working properly, or you got an email from someone you know that just doesn’t seem right, use Windows Defender to check for malware you might have downloaded inadvertently.