Wirebook › Glossary › IP address
What is an IP address?
In one sentence: The number that identifies a computer on the internet, like 192.0.2.10.
A little more
Every device on the internet needs an address so that messages can find it. The older IPv4 kind looks like 192.0.2.10; the newer IPv6 kind is much longer, like 2001:db8::1, because the world ran out of IPv4 numbers.
Your home router usually has one public address and gives your devices private ones inside the house. Websites see the public one, which roughly reveals your internet provider and area, not your street.
You can spot the private kind by how it starts: 192.168, 10, or 172.16 up to 172.31. Those numbers are reused inside millions of homes, so they only mean something on your own network. 127.0.0.1 is special too: it always means this same device, which is what the name localhost points to.
See it in action
- 1What happens when you open a web page?Follow one click from your keyboard to a server and back: DNS, the padlock handshake, HTTP, tunnels and painting the page.6 min · interactive
- 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
Free grown-up tools and guides on Tooltern, our sister site. They work in your browser and nothing is uploaded.