Epoll is a scalable I/O event notification system used in Linux to manage multiple file descriptors efficiently. It allows applications to monitor many connections simultaneously without the overhead of constantly polling each one. This is particularly useful for servers handling numerous client requests, as it reduces CPU usage and improves performance. The Epoll interface provides three main functions: epoll_create, epoll_ctl, and epoll_wait. These functions enable developers to add, modify, or remove file descriptors from the monitoring list and wait for events to occur. This makes Epoll a preferred choice for high-performance network applications.