What is a port?

In computer networking, a port or port number is an application-specific or process-specific communications endpoint used by Transport Layer protocols, such as Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) of the Internet Protocol Suite.

Port number ranges

Port numbers are divided into three ranges: the Well Known Ports, the Registered Ports, and the Dynamic and/or Private Ports.

The Well Known Ports are those from 0 through 1023. DCCP Well Known ports SHOULD NOT be used without IANA registration.

The Registered Ports are those from 1024 through 49151. DCCP Registered ports SHOULD NOT be used without IANA registration.

The Dynamic and/or Private Ports are those from 49152 through 65535

A value of 0 in the port numbers registry below indicates that no port has been allocated.

TCP and UDP ports

The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) are Transport Layer protocols used within the Internet Protocol Suite for communication between computers. The Internet Assigned Numbers Authority (IANA) is responsible for maintaining the official assignments of port numbers for specific uses.