An IP address is a unique set of numbers that identifies a computer connected to the Internet, or any other network. The computer needs this identity so that other computers can send it data, and vice versa. It is similar to people having a postal address.
Every device on a network, including servers, routers, printers, modems and individual computers has an IP address. Individual website domains also have IP addresses.
The most common form of IP address in use today is IPv4 (IP version 4). It takes the format of four sets of numbers separated by a dot (for example, 194.168.0.24). They perform similar functions to country, state, and street name and number in a postal address.
The Internet Assigned Numbers Authority (IANA) manages the international allocation of IP addresses, along with other regional authorities. They allocate blocks of IP addresses to Internet Service Providers (ISP) who then allocate individual IP addresses to their customers.
IP addresses are either “static” or “dynamic”. A static IP address is manually allocated to an individual device and kept by that device each time it connects to the network. A dynamic IP address is automatically allocated each time that device connects to the network. For example, each time a home computer connects to the Internet it will be allocated an available IP address from the ISP’s collection of addresses. This enables the use of fewer addresses for thousands of devices.
When individual website domains are allocated, they are also given an IP address by the ISP that hosts the website (the IP address will change when the host changes). For example, the IP address for www.google.com at the time of writing was 66.249.89.147.
Due to the increasing numbers of computers on the Internet, the availability of IPv4 addresses (32-bit) will eventually decline, therefore, the IANA launched IPv6 in 1999, which is written in a format (128-bit) that will allow for further Internet growth (for example, 2001:0db8:582:ae33::29).
