Port

A port is a transport-layer 16-bit address (0-65535) that distinguishes multiple network applications on one host; combined with the IP address it forms a socket.

Purpose

It lets one host run many network services at once, told apart by port number.

Mechanism

Ports 0-1023 are well-known (HTTP 80, HTTPS 443, SSH 22), 1024-49151 are registered, and 49152-65535 are dynamic/private. IANA maintains the assignments. A socket = (IP, port).

Use cases

Web servers listening on 80/443
Databases on 3306/5432
SSH on 22
Custom service ports

Examples

Input
```
TCP 443
```
Output
```
The well-known port for HTTPS
```
IANA-assigned

Common errors

Port conflicts (two services on the same port): Move to another port or put a reverse proxy in front

Related terms

A socket is a network communication endpoint identified by (protocol, local IP, local port, remote IP, remote port), serving as the interface between the application and transport layers.

TCP (Transmission Control Protocol) is a connection-oriented, reliable, ordered transport-layer protocol, establishing connections with a three-way handshake and providing sliding-window flow control and ACK-based acknowledgment.

UDP (User Datagram Protocol) is a connectionless, unreliable, unordered transport-layer protocol with low overhead and minimal delay, suited to real-time and broadcast traffic.

Related tools

Look up common network ports and services. Free, private, 100% client-side.

References