An IP address (short for Internet Protocol address) is a numeric label assigned to a network interface so that devices can find and communicate with one another across a computer network such as the local network or the internet. It functions much like a postal address: it indicates where packets of data should be delivered and how to route them between networks. Devices implement addressing using the rules of the Internet Protocol family to exchange information.

Format and major versions

There are two widely used versions of IP addresses. IPv4 addresses use 32 bits and are commonly represented in dotted-decimal form (for example, 192.0.2.1). IPv6 uses 128 bits and is written in hexadecimal fields separated by colons (for example, 2001:db8::1). The larger address space of IPv6 was developed because IPv4 addresses became scarce as the internet expanded. Internally these addresses are binary values; textual forms exist to make them easier to read and share.

Types and practical distinctions

  • Public vs private: Public addresses are globally routable on the internet; private addresses are reserved for use within local networks and are not routed across the public internet without translation.
  • Static vs dynamic: A static address is manually assigned and remains constant; a dynamic address is assigned temporarily, typically by DHCP.
  • Unicast, multicast, broadcast: Addressing modes determine whether packets target a single interface, multiple recipients, or all hosts on a network segment.

Assignment, routing and translation

Address allocation is coordinated at global and regional levels and delegated to network operators and service providers. On local networks, DHCP commonly issues addresses automatically. Network address translation (NAT) is often used to let many devices share a single public address. Routers consult routing tables to forward packets toward the destination based on the address and routing protocols.

Uses, limitations and notable facts

IP addresses are essential for web browsing, email, remote access, and most internet services. However, an address identifies a network interface rather than a person, so linking an address to an individual can be imprecise; locations derived from addresses are estimates and can be affected by intermediary networks. Security and privacy concerns arise because addresses can reveal network ownership or enable targeted attacks; techniques such as VPNs, proxies, and firewalls can alter or hide address information.

For further technical background and standards, see protocol specifications and network documentation resources such as addressing guides and introductory material on binary and notation like binary representation. For how the Internet Protocol is defined and evolves, consult protocol references and organizational guidance, for example standards and registries.