An Internet Protocol (IP) address is a number assigned to a device on a network so other systems know where to send data. When you open a website, stream video or send email, packets are labeled with source and destination IP addresses, much like postal addresses on envelopes.
IPv4 and IPv6
IPv4 addresses look like 192.0.2.1 — four numbers from 0 to 255. The world ran out of new IPv4 blocks years ago, so many networks share addresses using NAT. IPv6 uses longer hexadecimal strings such as 2001:db8::1 and provides a vastly larger address space. Modern networks often use both: IPv6 when available, IPv4 otherwise.
Public vs private addresses
Your home router usually hands out private addresses (for example 192.168.1.10) to phones and laptops. Those are not reachable from the open Internet. The public IP is what the rest of the world sees — typically one address shared by everyone on your Wi‑Fi through NAT. Use our IP lookup tool to see that public address.
Why IP addresses matter
Websites use IPs for routing, fraud prevention, content licensing and approximate localization. Lawful processes can sometimes tie an IP to an account or subscriber through an ISP. IPs are not perfect identity documents — they change, are shared, and can be routed through VPNs or proxies — but they are a fundamental part of how the Internet works.
Dynamic and static IPs
Most home connections use dynamic IPs that change occasionally when the modem reconnects. Servers and business lines may pay for static IPs that stay fixed for DNS records and firewall rules.
For more on reducing how much your IP reveals, read our guide on hiding your IP address.