A filter list in cybersecurity is a collection of rules or patterns used by software tools, such as adblockers or firewalls, to determine which network traffic, content, or elements should be blocked, allowed, or modified. These lists are typically maintained by communities or organizations and can target ads, trackers, malicious domains, or unwanted content. Filter lists are updated regularly to adapt to new threats and web technologies. Users can often customize which filter lists they use, enabling them to tailor their online experience and security level. Properly maintained filter lists are essential for effective content filtering and enhanced privacy.