What is a port in networking?
In one sentence: A numbered 'door' on a computer. Web traffic normally uses 443 (HTTPS) or 80 (HTTP).
A little more
One computer can run many services at once, so an IP address alone isn't enough. A port number (0 to 65535) says which service a message is for: 443 for HTTPS, 80 for plain HTTP, 22 for remote logins, and so on.
You rarely see ports in web addresses because browsers assume the usual one. If a URL has :8080 after the host, it's asking for a different door.
Your home router keeps every door shut to the outside world unless someone deliberately opens one. That is a good thing: a door left open, like remote desktop on 3389, is exactly what attackers knock on.
See it in action
- 2Anatomy of a web addressPaste any web address and see it taken apart, colour by colour: scheme, host, port, path, query and the fragment that never reaches the server.5 min · interactive
- BonusHow does the router know which device asked?Your home has one internet address but lots of screens.7 min · interactive
Do it for real
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