A listening port is a communication endpoint used by a device or server to accept incoming network connections from other devices. It operates at the Transport Layer (Layer 4) of the OSI model, using protocols like TCP or UDP. Each port is associated with a specific application or service, identified by a port number (ranging from 0 to 65535). For example, web servers typically use port 80 for HTTP and 443 for HTTPS. Ports must be open and configured correctly to allow communication. Administrators use tools like netstat or lsof to monitor or troubleshoot listening ports. Proper port management enhances security.
