A WAF, or Web Application Firewall, is a system that stands between your website or application and the rest of the internet, functioning as a barrier that blocks and protects your server against attacks by Hackers, Spammers, DDoS, SQL Injections and many other types. of Cyber Attacks.
WAF in a more technical way
While proxies generally only protect clients, WAF protects servers. A WAF is implemented to protect a specific web application or set of web applications and can be considered a reverse proxy.
The web application firewall is a highly scalable filter, where a set of rules are applied to an HTTP conversation, with the objective of protecting the application from common attacks, such as Cross-Site Scripting (XSS) and SQL Injection, before they reach hosting servers.