An application gateway is a security control operating at Layer 7 (application layer) of the network stack, functioning as both a load balancer and reverse proxy for web applications. It manages and distributes incoming traffic across multiple server instances while providing critical security features including an integrated Web Application Firewall (WAF) that inspects traffic to detect and block common vulnerabilities such as SQL injection, cross-site scripting (XSS), and other OWASP Top 10 threats.

Beyond traffic management, application gateways provide TLS/SSL offloading capabilities, decrypting encrypted traffic before it reaches backend servers to reduce processing overhead and simplify certificate management. This centralized approach enhances application performance, enforces advanced traffic routing rules, and protects against denial-of-service attacks, making it an essential component for securing public-facing applications in modern infrastructure environments.