epoll
epoll is a scalable I/O event notification mechanism for Linux, part of the kernel's event polling interface. It allows applications to efficiently monitor multiple file descriptors for I/O readiness, such as sockets, without busy-waiting or using multiple threads. It is widely used in high-performance network servers to handle thousands of concurrent connections with low overhead.
Developers should learn epoll when building scalable network applications on Linux, such as web servers, chat servers, or real-time systems, where handling many simultaneous connections is critical. It is essential for achieving high throughput and low latency in event-driven architectures, as it reduces CPU usage compared to older methods like select() or poll().