Web filtering is policy-based blocking or allowing of websites, categories, file downloads, or specific content. It is commonly enforced by firewalls, secure web gateways, DNS controls, and browser or endpoint agents. Rules may be based on domain reputation, URL category, MIME type, user identity, or time and location.
In cyber security, web filtering reduces exposure to phishing pages, malware delivery sites, command-and-control infrastructure, and unsafe or noncompliant content. It is a practical control for acceptable-use policy, data loss prevention, and web access governance. Attackers often try to bypass it with newly registered domains, compromised legitimate sites, URL shorteners, encrypted traffic, or domain fronting, so effective defenses usually combine filtering with logging, TLS inspection where appropriate, and alerting on policy violations.