Port Number
Port Number
A number that identifies which program should receive data sent over a network.
In Simple Terms
A port number is the number of the "window" that decides which app or service should receive data when you're exchanging information over the internet. For example, browsing a website and sending email each use a different number. Thanks to this numbering system, a computer can hand off incoming data to the correct app without any confusion.
Behind the Name
The word "Port" comes from the English term for a harbor. Just as ships choose one specific harbor out of many to deliver their cargo, data selects a specific "window" on a computer to arrive through — that's how the port number got its name. It's also sometimes called a "connection port" or "communication port."
Take a Closer Look!
A port number is a number used in network communication to identify which program on a computer or server data should be delivered to.
If an IP address is like a street address on the internet, a port number is like an apartment room number within that address.
Port numbers range from 0 to 65535 and are divided into several groups.
Numbers from 0 to 1023, known as "well-known ports," are reserved for commonly used services, while "registered ports" are used by specific applications.
For example, HTTP — the protocol used to view websites — uses port 80, while its secure version, HTTPS, uses port 443.
Without a port number, a computer could receive data but wouldn't be able to tell whether it should be opened in a web browser or an email client.
In short, port numbers act as traffic control, letting multiple apps use the internet at the same time without getting mixed up.