A port is an input or output of a unit. It can be a connection point for a peripheral device, peripheral units, or an application program. A port can be logical, physical, or both.
- A port is a connection point of a hardware unit. Usually an input/output channel of the computer or another hardware unit like modem, router, hub or multiplexer.
- In PBXs, the term port stands for a switchable connection position (e.g., a/b interface, ISDN channel) for in-house terminal equipment or access lines of the public network. For example, a basic access in ISDN has two ports, whereas a primary multiplex access has 30 ports.
- In IP terminology, a port is an upper layerprocess that receives its information from the layers below. Ports are numbered and each process has its specific port number. For example, HTTP has port 80, and Simple Mail Transfer Protocol( SMTP) has port 25. Therefore, in IP communications, the port number is noted in requests along with the Internet address.
- In SCSI, the physical port supports the connection of drivers and receivers to the SCSI bus cable. The logical SCSI ports form either the SCSI initiator port or the SCSI target port. It is the logical instance that creates a process or processes SCSI commands.
- In Fibre Channel, the port provides the physical interface to other FC ports. Such a port includes the transmitter, the receiver, and the associated logics within the node. A node can comprise several ports, each of which is identified by its own Port_ID. This port name consists of a 64 bit long address, which is unique in the world and is used in Fibre Channel for routing.