Definition: IP address

(Internet Protocol address) The address of every connected device in a TCP/IP network, which is the worldwide standard for the Internet as well as local networks in homes and companies. Every desktop and laptop computer, server, scanner, printer, modem, router, smartphone, tablet and smart TV is assigned an IP address, and every packet (Web, email, video, etc.) traversing an IP network contains source and destination IP addresses.

Public and Private Addresses
For homes and small businesses, the entire local network (LAN) is exposed to the Internet via one public IP address. Large companies may have several public IPs.

In contrast, the devices within the local network use private addresses not reachable from the outside world, and the router enforces this standard. The same private address ranges are used in every network, which means every computer within the company has the identical private IP address of some computer in thousands of other companies. See private IP address and NAT.

Logical vs. Physical
An IP address is a logical address that is assigned by software in the router or server, and that logical address can change from time to time. For example, when you turn a laptop on in a new hotspot, it will get a new UP (see DHCP).

However, there is a physical address built into every unit of hardware, which cannot change (see MAC address). In order to locate a device in an IP network, the logical IP address is converted to a physical address by a resolution protocol (see ARP).

Static and Dynamic IP
Network infrastructure such as servers, routers and firewalls are assigned permanent "static" IP addresses. A user's machine can also be assigned a non-changing static IP by the network administrator; however, it is generally configured to accept an address generated by software (see DHCP).

Version 4 and 6 (IPv4 and IPv6)
The original IP Version 4 addressing scheme defined 32 bits to hold the IP address. However, a larger Version 6 address was later created, and both are in use. It will take a long time before the newer IPv6 is the only one needed. See IPv4 addressing.

What's My IP Address?

This is one of several websites that report the user's IP by merely going to the site. Internet service providers may periodically change the IP of home users, who are entirely unaware of this change unless they go to IP Chicken or a similar site. Business users with websites that face the public have "static" IPs that rarely change. See dynamic IP address and static IP address.