On the spectrum of software there’s clean apps on one end, malware on the other, and a grey area in between of apps that we don’t have a lot of confidence in, or that may display some disturbing behavior, but don’t fall to the level of malware.
Malware is malicious software. It may be a self-replicating virus, a "trojan horse" that pretends to be something it's not in order to trick you into installing it, or some other kind of attack. Its goal may be to steal your data, steal your identity, use your system to launch attacks against others, or commit other cybercrimes. Microsoft Defender Antivirus tries to block malware before it can infect your device.
Potentially unwanted apps (PUA) aren't malware, but they might display advertising, use your PC for cryptomining, or do other things you'd prefer they not do.
For the potentially unwanted apps, Windows 10 can let you know that we have concerns, and let you decide if you want to proceed with installing them or not. For more information about turning on protection from potentially unwanted apps see Protect your PC from potentially unwanted software.
For more information on how Microsoft classifies malware, unwanted software, and potentially unwanted apps see How Microsoft identifies malware and potentially unwanted applications.
Minimize the possibility of unwanted software getting onto your PC
- Download apps only from trusted sources, such as Microsoft Store, and be thoughtful about which apps you install.
- Make sure you're running a regularly updated antivirus product such as Microsoft Defender Antivirus, which is built into Windows 10.
- Use a modern browser, such as the new Microsoft Edge. Microsoft Edge uses Microsoft Defender SmartScreen, which helps block potentially unwanted apps.
- Keep your device up-to-date with the latest updates for Windows, your browser, and your apps.
Reboot your PC at least once a week. This can help it run more smoothly and make sure you get the latest updates installed regularly.
If you believe you have unwanted software
- Uninstall software you don’t need using Add or Remove Programs.
- In Windows Security, get the latest definitions and then run a full scan with Microsoft Defender Antivirus. Learn how
- If the unwanted software persists, you can submit the files to Microsoft.
- Perform an offline scan with Microsoft Defender Offline.
If you're in an enterprise, see the Microsoft Security Intelligence website for in-depth information about unwanted software.