What is an IP address?

Every device that talks to the internet needs an address so that answers can find their way back to it. That address is an IP address: a number assigned to your connection by whoever runs the network you are on. When you open a page, your request carries your address the way a letter carries a return address, and the server sends the page back to it.

That is the entire idea. The details below explain what the number looks like, who hands it out, why you have more than one, and what someone can and cannot learn from it.

What the number looks like

There are 2 versions of the Internet Protocol in use, and each has its own address format.

	IPv4	IPv6
Example	203.0.113.17	2001:db8:85a3::8a2e:370:7334
Length	32 bits, written as 4 numbers from 0 to 255	128 bits, written as up to 8 groups of hexadecimal digits
Total addresses	About 4.3 billion	About 340 undecillion (3.4 × 10^38)
Status in 2026	Still carries most traffic; addresses are exhausted and traded	Growing; most mobile carriers and large providers offer it

IPv4 ran out of fresh addresses more than a decade ago, which is why providers share them between customers and why IPv6 exists. Most connections today are dual-stack, meaning they have one of each, and your browser picks whichever works better for a given site. The glossary entries on IPv4 and IPv6 describe each format in detail, and the guide to IPv4 vs IPv6 explains how to tell which one you are using.

Who assigns IP addresses

Addresses are not picked at random. The Internet Assigned Numbers Authority holds the global pool and delegates large blocks to 5 regional registries, one per part of the world. The registries allocate smaller blocks to internet providers, hosting companies, universities and large businesses. Each of those organizations runs an autonomous system, identified by an ASN, and announces its blocks to the rest of the internet so that traffic can be routed to them.

Your provider then assigns one address from its block to your connection. That chain, registry to organization to you, is public record. It is why a lookup of any address can name the organization behind it and the country where the block is registered, even though it cannot name the subscriber.

Public and private addresses

A home with a router, 3 phones, 2 laptops and a TV does not use 7 public addresses. The provider gives the router 1 public address, and the router hands every device a private address from a range reserved for exactly this purpose.

Range	Addresses	Typical use
10.0.0.0 to 10.255.255.255	About 16.8 million	Corporate networks, some ISPs, VPN tunnels
172.16.0.0 to 172.31.255.255	About 1 million	Business networks, container platforms
192.168.0.0 to 192.168.255.255	65,536	Home routers (192.168.0.x and 192.168.1.x are the usual defaults)
100.64.0.0 to 100.127.255.255	About 4 million	Carrier-grade NAT between an ISP and its customers

Private addresses are never routed on the public internet, so the same 192.168.1.5 exists in millions of homes without conflict. The router rewrites outgoing packets so they carry its public address, and rewrites the replies back to the right device. That translation is NAT, and it is the reason a settings screen on your laptop and a website report different addresses for "your IP". There is a separate walkthrough on how to find your IP address on each platform if you need the exact menu paths.

Carrier-grade NAT adds a second layer: the provider gives your router a private-style address and shares one public address among many customers. On mobile networks this is the norm, which is why thousands of phones can appear to a website as the same IP.

Special addresses you will run into

A few addresses are neither public nor private in the usual sense, and recognizing them saves confusion when troubleshooting.

Address	Meaning
127.0.0.1 and ::1	Loopback: the device talking to itself. A server on "localhost" is reachable only from the same machine.
169.254.x.x	Link-local: self-assigned when a device could not get an address from DHCP. Seeing one usually means the router or cable is the problem.
fe80:: addresses	IPv6 link-local: every IPv6 device has one for its local network; it says nothing about internet access.
0.0.0.0	"Any address": used by servers to listen on every interface, or shown when no address is configured.
255.255.255.255 and x.x.x.255	Broadcast: a packet to everyone on the local network.

If a settings screen shows a 169.254 or fe80 address and nothing else, the device is not actually connected to the internet, whatever the Wi-Fi icon says.

Static and dynamic addresses

A dynamic address is leased to you for a period and may change when the lease ends, when you restart your modem or when the provider reorganizes its pool. Nearly all consumer connections work this way; it lets a provider serve more customers than it has addresses and makes you slightly harder to track over time.

A static address stays the same until the contract changes. Servers need one so that DNS records keep pointing at them, and business lines usually include one. On home plans it is normally a paid option. A static address is not more "real" or more trusted than a dynamic one; what matters to websites is the network it belongs to, not whether it changes.

What an IP address reveals

Because the allocation chain is public, a single address reveals a surprising amount about the connection, and surprisingly little about the person.

It reveals	How reliable	Where it comes from
Country	Very reliable	Registry records and routing data
Region and city	Approximate, often a neighboring city	Where the provider registered the block, plus measurements
The organization that routes it	Reliable	The announcing autonomous system
Network type: home ISP, mobile carrier, datacenter, VPN provider	Reliable at the network level	Classification of the organization and its ranges
Time zone of the network	Usually	Derived from the location estimate
Abuse history	Depends on the list	DNS blocklists and reputation feeds

That combination is what fraud and anti-abuse systems act on. A login from a datacenter address, a time zone that disagrees with the address's country, or a listing on a spam blocklist each raise the suspicion score even though none of them identifies you. You can see the full profile of your own address, or anyone else's, with the IP lookup, and the one-line verdict a strict site would reach with the IP checker. The accuracy limits of the location part are described under IP geolocation.

What an IP address does not reveal

• Your name or street address. Only the provider holds the mapping between a subscriber and an address at a given time, and it releases it only under legal process.
• Your exact location. City-level estimates are based on where the block is registered and on latency measurements, not on GPS. Mobile addresses are often placed at the carrier's gateway, hundreds of kilometers from the phone.
• Your browsing history. A website sees only the requests you send to it. Your provider sees the names you look up through its DNS and the servers you connect to, but not the content of encrypted pages.
• Which person in a household sent the request. Every device behind the router shares the public address.
• Whether you are using a proxy. Nothing in a packet says "proxy". Detection works by classifying the network and looking for contradictions, which is why a well-configured residential connection passes and a datacenter address does not.

Why the type of network matters more than the number

Two addresses can be one digit apart and be treated completely differently, because trust is assigned per network, not per address. An address from a consumer provider reads as a person at home, one from a mobile carrier as a phone that shares its address with many others, and one from a hosting company as a server, a bot or a VPN exit. Sites decide how much friction to apply, from none to a captcha to an outright block, largely on that classification. The glossary entries on residential IP and datacenter IP explain each category and the signals behind it, and the ASN lookup shows which network a given address belongs to and how it is classified.

How to see your own

The public address of your current connection, with its country, provider and network type, is shown at the top of the homepage. Private addresses live in your device's network settings. The difference between the 2 is the first thing to understand before troubleshooting a connection, setting up port forwarding or checking whether a VPN or proxy is doing its job, and the rest of this blog builds on it.