GLOSSARY · INTERNET PROTOCOL ADDRESS
IP address
An IP address is a number that identifies a device or network connection on the internet, in the way a street address identifies a building. Data sent across the internet is labelled with the address it came from and the address it is going to, so replies know where to return.
Why it matters
Websites see your public IP address on every request. From it they can estimate your country and city, learn which internet provider you use, and decide whether to treat you as a home user, a business or a server. Because the address is attached to a network connection, not to you personally, it is a clue and not a name.
In practice
Your address can change when you restart your router, switch networks, or use a VPN or proxy. Phones switch between a home address and a carrier address as they move. To see the one websites see right now, open the tool below, and compare it with the address you see in your device's network settings, which is often a different, private one.
Related terms
- IPv4: IPv4 is the older and still most common version of the internet's addressing system.
- IPv6: IPv6 is the newer version of the addressing system, built to replace IPv4.
- Public vs. private IP address: A public IP address is reachable across the internet and is the one websites see.
- ASN: An ASN is a unique number assigned to a network that manages its own routing on the internet, such as an internet provider, a cloud company, a university or a large business.