Anti-spam filters are tools used to identify and block unwanted or harmful emails, commonly known as spam. They analyze incoming messages based on various criteria, such as keywords, sender reputation, and user behavior. By filtering out these unwanted emails, they help keep inboxes organized and reduce the risk of phishing attacks. These filters can be found in many email services, including popular platforms like Gmail and Outlook. Users can often customize their settings to adjust the level of filtering, ensuring that important messages are not mistakenly marked as spam.