Socket
A socket refers to a communication endpoint that allows two processes to exchange data over a network. Sockets provide a mechanism for processes on different devices to communicate with each other, whether they are on the same machine or across the Internet.
PHP provides a set of functions for working with sockets, allowing developers to create both client and server applications that can communicate over networks using various protocols, including TCP and UDP.
<?php
$server = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_bind($server, '127.0.0.1', 8080);
socket_listen($server);
$client = socket_accept($server);
?>