Term:IP address [Internet Protocol Address]
An IP address, short for Internet Protocol Address, is a number used to identify a device connected to a TCP/IP network like the internet.
In IP version 4 (IPv4), an address is a 32-bit number typically displayed as four decimal numbers ranging from 0 to 255, separated by periods. 18.104.22.168 is an example of a valid IP address. (IP version 6 uses 128 bits, and is typically displayed using hexadecimal notation separated by colons, with some portions being optional.)
Every device connected to a TCP/IP network is required to have a unique IP address. It’s important to realize that an IP address is assigned to a device, and that device then in turn may be capable of hosting many different and potentially unrelated services, including websites.
The internet itself is, of course, the largest TCP/IP network, and every device connected directly to it does, indeed, have a unique IP address. Confusion sometimes results from the fact that many devices are actually not connected directly to the internet, but rather through some other device, such as a router.
A router, as a device connected to the internet, is assigned an IP address on the internet, but it also establishes a completely separate network (or LAN) on which attached devices are assigned IP addresses that are unique to that local network. The router, then, handles Network Address Translation (or NAT) to give the local devices the ability to contact services on the internet, where they appear as connections from the router’s internet IP address.
An Internet Protocol address (IP address) is a numerical label such as 192.0.2.1 that is connected to a computer network that uses the Internet Protocol for communication. An IP address serves two main functions: host or network interface identification and location addressing.
Internet Protocol version 4 (IPv4) defines an IP address as a 32-bit number. However, because of the growth of the Internet and the depletion of available IPv4 addresses, a new version of IP (IPv6), using 128 bits for the IP address, was standardized in 1998. IPv6 deployment has been ongoing since the mid-2000s.
IP addresses are written and displayed in human-readable notations, such as 192.0.2.1 in IPv4, and 2001:db8:0:1234:0:567:8:1 in IPv6. The size of the routing prefix of the address is designated in CIDR notation by suffixing the address with the number of significant bits, e.g., 192.0.2.1/24, which is equivalent to the historically used subnet mask 255.255.255.0.
The IP address space is managed globally by the Internet Assigned Numbers Authority (IANA), and by five regional Internet registries (RIRs) responsible in their designated territories for assignment to local Internet registries, such as Internet service providers (ISPs), and other end users. IPv4 addresses were distributed by IANA to the RIRs in blocks of approximately 16.8 million addresses each, but have been exhausted at the IANA level since 2011. Only one of the RIRs still has a supply for local assignments in Africa. Some IPv4 addresses are reserved for private networks and are not globally unique.
Network administrators assign an IP address to each device connected to a network. Such assignments may be on a static (fixed or permanent) or dynamic basis, depending on network practices and software features.