Every device that talks on the internet needs an address, the way every letter needs a destination. An IP address (Internet Protocol address) is that destination: a number that tells routers where to deliver a packet and where to send the reply.
Two versions, one job
There are two kinds of IP addresses in use today:
- IPv4 addresses are 32-bit numbers written as four decimal numbers:
203.0.113.42. There are about 4.3 billion of them, which turned out not to be enough. - IPv6 addresses are 128-bit numbers written in hexadecimal:
2001:db8:4f2a::17. There are enough of them to give every device its own address many times over.
Most connections today have both. Your browser picks one per connection — usually IPv6 when it works. The homepage shows both if your network supports them.
Who gives you an IP address?
Address space is managed in a hierarchy. IANA allocates large blocks to five regional internet registries (RIRs) — ARIN, RIPE NCC, APNIC, LACNIC and AFRINIC. They assign blocks to internet service providers, hosting companies and large organisations, which in turn assign addresses to customers and devices.
That chain is public. Look up any address and you can see the network that announces it (ASN), the organisation it is registered to (WHOIS) and the route that covers it.
Public and private addresses
Your laptop probably doesn’t have a public IP address of its own. Home and office networks use private addresses such as 192.168.1.20 internally, and the router translates them to its single public address with NAT. Every device behind that router appears to the outside world with the same public IP.
Mobile carriers often go a step further and share one public IPv4 address among many customers (carrier-grade NAT). That’s one reason IPv6 matters: it removes the need to share.
What an IP address reveals
An IP address tells a website:
- which network you’re on — your ISP, mobile carrier, company, VPN or cloud provider;
- roughly where that network is used — usually the country, sometimes the region or city;
- some properties of the connection — whether it belongs to a hosting provider, a VPN or the Tor network, if a database has classified it.
It does not reveal your name, your street address or your exact location. IP geolocation describes where an address block is likely used, which is often the location of the provider’s equipment rather than the user. Precise location requires your explicit permission through the browser.
Does my IP address change?
Often, yes. Most home and mobile connections get a dynamic address from the provider’s pool, which can change when the router reconnects. Businesses and servers usually have static addresses. With IPv6, devices also rotate the last part of their address regularly for privacy.
Try it
- See your own address and what the internet sees about your connection.
- Look up any IP address to see its network, route and approximate location.
- Learn more about IPv4 and IPv6.