SmartScreen is a security feature developed by Microsoft that helps protect users from malicious websites and downloads. It works by checking URLs and files against a database of known threats, warning users if they attempt to access potentially harmful content. This feature is integrated into various Microsoft products, including the Edge browser and Windows operating system. In addition to blocking harmful sites, SmartScreen also provides safety ratings for websites and downloads. If a site is deemed unsafe, users receive a warning message, allowing them to make informed decisions about their online activities. This helps enhance overall internet safety and user experience.