Azure Application Gateway is a web traffic load balancer that enables you to manage traffic to your web applications. It provides features like SSL termination, URL-based routing, and session affinity, which help improve the performance and security of your applications. This service operates at the application layer (Layer 7) of the OSI model, allowing it to make routing decisions based on the content of the request. With built-in application firewall capabilities, Azure Application Gateway helps protect your applications from common web vulnerabilities, ensuring a safer user experience.