With more than 1 billion devices running Windows 10 we see a lot of signals that can help us protect customers from potentially unwanted, or malicious, apps, files, and websites. Apps, files, or sites that exhibit potentially dangerous behavior, are untrusted, or have been created by publishers with a reputation for unsafe apps or sites, can be identified and blocked.
Likewise apps or sites that are signed or created by well-known, and trusted, publishers may be allowed more easily.
In the Windows Security app there are several kinds of reputation-based protection.
Check apps and files
This toggle turns on Microsoft Defender SmartScreen to evaluate the reputation of apps and files you may download from the web.
SmartScreen for Microsoft Edge
When you're using the new Microsoft Edge as your browser, Microsoft Defender SmartScreen can help evaluate websites or downloads to see if they are known to be malicious, such as phishing sites, or tech support scams.
If you try to go to a site that is known to be dangerous, SmartScreen will show you a warning screen that clearly identifies the suspected threat and gives you a chance to close the browser tab before anything bad can happen.
When you attempt to download a file that SmartScreen finds suspicious, Edge will warn you that the file may be untrusted and give you the opportunity to cancel the download before it takes place.
Potentially unwanted app blocking
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. Microsoft Defender will try to identify those apps for you and block them before they can install, or download, and cause issues with your system.
For more information see Protect your PC from potentially unwanted applications.
SmartScreen for Microsoft Store apps
While Microsoft Defender SmartScreen can protect you from malicious files or apps you may encounter in the Microsoft Edge browser, SmartScreen for Microsoft Store provides another check on content that is used by Microsoft Store apps. This is just another layer of security to protect you.
