An Internet Protocol address is a numeric label used to deliver packets to an interface on an IP network. It identifies where traffic should go in a routing context—not a permanent person, computer, or street address.
An address depends on where you are looking
Your laptop can have a private Wi-Fi address, a loopback address for talking to itself, one or more IPv6 addresses, and a public address shared through the router. A VPN can add virtual interfaces and present a different public exit address to websites.
| Address type | Example | Used for |
|---|---|---|
| IPv4 private | 192.168.1.42 | Communication inside a local network. |
| IPv4 loopback | 127.0.0.1 | A device talking to itself. |
| IPv6 link-local | fe80::/10 | Communication on the local link. |
| Public address | Assigned by a provider | Routing across the public internet. |
Public vs. private
A public IP address is globally routable on the internet. Your ISP assigns or delegates it to your connection. A private IPv4 address is intended for local networks and is not routed across the public internet.
The familiar private IPv4 ranges are:
10.0.0.0/8— 10.0.0.0 through 10.255.255.255172.16.0.0/12— 172.16.0.0 through 172.31.255.255192.168.0.0/16— 192.168.0.0 through 192.168.255.255
Two unrelated homes can both use 192.168.1.20 because that address only needs to be unique inside each private network.
Static vs. dynamic
Dynamic describes how an address is assigned or how long it is expected to remain. Home routers commonly use DHCP to lease private addresses, and ISPs often assign public addresses dynamically. A lease can be renewed with the same address many times, so “dynamic” does not mean “changes every day.”
A static address stays fixed by configuration or service agreement. Public static addresses are useful when a stable inbound endpoint is required. Inside a LAN, a DHCP reservation is often safer than manually configuring the device because the router keeps address management in one place.
What NAT does—and where CGNAT changes the picture
Most IPv4 home routers use network address translation. Outbound connections from many private devices are represented through one public address, while the router tracks which reply belongs to which device.
Inbound connections require an explicit mapping such as port forwarding, plus a listening service and firewall permission. Even then, the connection may fail if the ISP places the customer behind carrier-grade NAT (CGNAT), where multiple subscribers share a provider-controlled public IPv4 address.
100.64.0.0/10, and it differs from the public address shown on this site, inbound IPv4 port forwarding may require help from the ISP.Why IPv6 looks different
IPv4 has about 4.3 billion possible addresses before accounting for reservations. IPv6 uses 128-bit addresses, written in hexadecimal, creating a vastly larger address space. A compressed address might look like 2001:db8:1234::42.
IPv6 generally gives interfaces globally routable addresses without traditional IPv4 NAT. That does not mean devices are automatically exposed: stateful firewall policy on the router and host still controls unsolicited inbound traffic. An interface may also use temporary IPv6 addresses for outbound privacy.
How subnets divide a network
A prefix such as /24 marks the network portion of an IPv4 address. The remaining bits identify addresses inside that subnet. With 192.168.1.42/24, the network is 192.168.1.0, the traditional broadcast is 192.168.1.255, and ordinary host addresses run between them.
Use the subnet calculator to see how changing the prefix changes the mask, range, and address count.
What your public IP can reveal
An IP can reveal the provider or organization that controls its block, an approximate region, and clues such as whether traffic exits through a hosting provider or VPN. Geolocation databases can be stale or place an address at the provider’s facility rather than the user’s location.
An IP alone does not reliably reveal a person’s name or exact address. An ISP may be able to associate a customer with an address at a particular time using its account and lease records, subject to applicable legal process and retention practices.