Port

A port is a virtual point where network connections start and end. Ports are software-based and managed by a computer's operating system. Each port is associated with a specific process or service and there are default ports for common services.

Ports allow computers to easily differentiate between different kinds of traffic: emails go to a different port than webpages, for instance, even though both reach a computer over the same Internet connection.

Ports are standardized across all network-connected devices, with each port assigned a number. While IP addresses enable messages to go to and from specific devices, port numbers allow targeting of specific services or applications within those devices.

Ports are a transport layer concept. Only a transport protocol such as the Transmission Control Protocol or User Datagram Protocol can indicate which port a packet should go to.

Info

There are 65,535 possible port numbers, although not all are in common use