Cybersecurity definition
What is WAF?
WAF stands for Web Application Firewall.
By Cyber Tool Stack Editorial TeamUpdated
Definition
A filter that sits in front of a web application or API, inspecting incoming requests for attack patterns like SQL injection and cross-site scripting and blocking them before they reach the application.
Where WAF fits in the security landscape
These beginner lessons use this term while explaining the surrounding security control.
Related cybersecurity terms
DDoSDistributed Denial-of-ServiceAn attack that floods a target with traffic from many sources at once — often a botnet — to overwhelm its capacity and knock it offline for legitimate users.OWASP Top 10A regularly updated, community-researched ranking of the most critical web application security risks, published by the OWASP Foundation and widely used as a baseline checklist for secure development. The current edition, OWASP Top 10:2025, was the first major update since 2021.