An IP address is the number that lets two machines on a network find each other. IP stands for Internet Protocol, the set of rules that governs how data moves across the internet, and the address is the part of those rules that answers a simple question: where should this data go?
The postal analogy is imperfect but useful. When you request a web page, your device sends a small packet of data that says, in effect, "send me this page, and here is where to deliver it." Without a return address, the server would have nowhere to send the answer.
What one looks like
The familiar form is four numbers separated by dots, each between 0 and 255:
203.0.113.42
That is IPv4, and behind it sits a 32-bit number. Thirty-two bits allow about 4.3 billion unique combinations, which was more than anyone in the 1980s imagined the world needing. It ran out.
The replacement, IPv6, looks quite different:
2001:0db8:85a3::8a2e:0370:7334
That is 128 bits, written in hexadecimal, with runs of zeros collapsed into a double colon. The address space is large enough that exhausting it is not a practical concern.
Public and private addresses
This is the distinction that clears up most confusion, so it is worth being precise.
Your public IP address belongs to your router and is visible to the entire internet. Every website you visit sees it. It is what our what is my IP page shows you.
Your private IP address identifies one device inside your own network. It usually
starts with 192.168., 10. or 172.16. through
172.31.. These ranges are reserved and are never routed on the public internet, which
means millions of homes can use 192.168.1.1 at the same time without conflict.
| Public address | Private address | |
|---|---|---|
| Assigned by | Your internet provider | Your own router |
| Visible to websites | Yes | No |
| Unique worldwide | Yes | No — reused everywhere |
| Shared by your devices | Yes, all of them | No, one per device |
| Typical example | 203.0.113.42 | 192.168.1.14 |
The bridge between the two is Network Address Translation. Your router keeps a table of which internal device asked for what, rewrites outgoing packets to carry the public address, and reverses the process on the way back. It is why a household of fifteen devices needs only one public address, and it is the main reason IPv4 survived long past the point it should have run out.
Where addresses come from
Allocation is hierarchical. A global body, IANA, hands large blocks to five regional registries — ARIN for North America, RIPE NCC for Europe and the Middle East, APNIC for Asia-Pacific, LACNIC for Latin America and AFRINIC for Africa. Those registries allocate smaller blocks to internet providers, who assign individual addresses to customers.
This chain is public, and it is exactly why an IP lookup can tell you the provider and organisation with high confidence while only estimating the city.
Dynamic and static
Most home connections get a dynamic address, leased for a period and renewed automatically. It may or may not change when the lease renews or the router reboots. A static address is permanently assigned, costs more, and matters only if you are hosting something that others need to find reliably.
What your IP address reveals
It reveals less than most people fear and more than most people expect. Realistically, a website can infer:
- Your approximate city or region, with meaningful error bars
- Your country, almost always correctly
- Your internet provider and its autonomous system number
- Whether you are on a home line, a mobile network, a corporate network or a data centre
- Your rough time zone
It does not reveal your name, your street address, your email, anything stored on your device, or which member of the household is browsing.
The honest summary: your IP address identifies your connection, not you. Turning a connection into a person requires records only your provider holds.
Why yours might change
A dynamic lease expiring, a router restart, moving between Wi-Fi and mobile data, connecting to a VPN, or your provider reorganising its network — any of these can hand you a new address. On mobile it can change several times a day as you move between towers. None of this indicates a problem.
Where to go next
If you want to see your own, the homepage shows it along with your provider and approximate location. To understand the two versions in more depth, read IPv4 vs IPv6. If your interest is privacy, the honest guide to hiding your IP address explains what actually works.