kqueue is an event notification interface used in BSD operating systems, designed to efficiently monitor multiple file descriptors to see if they are ready for reading, writing, or have encountered errors. It allows applications to handle many simultaneous connections without the overhead of constantly polling each descriptor, making it suitable for high-performance network servers. The kqueue mechanism works by creating a kernel-level queue that tracks events associated with file descriptors. When an event occurs, such as data becoming available to read, the application is notified, allowing it to respond promptly. This results in improved resource management and responsiveness in applications.