The quick answer
An Internet Protocol address is a numerical label used to route data between devices and networks. When your browser asks a website for a page, an IP address helps the response travel back to the correct internet connection.
The address visible to a website is usually the public IP assigned to your router, mobile carrier, company network or VPN server. It is different from the private address used by a phone or laptop inside a local network.
What an IP address does
Internet traffic is divided into packets. Each packet carries addressing information so routers can forward it across multiple networks. The destination address tells the network where the packet is going, while the source address provides a route for replies.
An IP address identifies a network interface at a moment in time. It is not a permanent identity for a person. Home connections often receive dynamic addresses, mobile devices move between carrier gateways and VPNs replace the public address seen by websites.
- Routes requests and responses between networks
- Helps websites return data to the correct connection
- May change when you reconnect, travel or use a VPN
- Does not reveal a precise street address by itself
IPv4 and IPv6 formats
IPv4 addresses contain four decimal numbers separated by periods, such as 192.0.2.10. The format has about 4.3 billion possible addresses, so providers commonly share public IPv4 addresses through network address translation.
IPv6 addresses use hexadecimal groups separated by colons. The much larger address space supports the continuing growth of connected devices. Many networks run both protocols together in a dual-stack configuration.
What websites can learn from it
A public IP can reveal the internet provider and an approximate country, region or city. Accuracy varies because geolocation databases map network ownership and routing information rather than reading a device's GPS position.
Websites also receive ordinary browser request information. Privacy tools can reduce some signals, but an internet service must still receive a routable address to send a response to your connection.