IP Address

(From Wikipedia, the free encyclopedia)

An IP address (Internet Protocol address) is a unique number, a kind of telephone number, used by machines (usually computers) to refer to each other when sending information through the Internet. This allows machines passing the information onwards on behalf of the sender to know where to send it next, and for the machine receiving the information to know that it is the intended destination.

An example IP address is Converting to such numbers from the more human-readable form of domain addresses, such as www.wikipedia.org, is done via the Domain Name System. The process of conversion is known as resolution of the domain name.


More detail

The Internet Protocol (IP) knows each logical host interface by a number, the so-called IP address. On any given network, this number must be unique among all the host interfaces that communicate through this network. Users of the Internet are sometimes given a host name in addition to their numerical IP address by their Internet service provider.

The IP addresses of users browsing the world wide web are used to enable communications with the server of the web site. Also, it is usually in the header of email messages one sends. In fact, for all programs that utilize the TCP/IP protocol, the sender IP address and destination IP address are required in order to establish communications and send data.

Depending on one's Internet connection the IP address can be the same every time one connects (called a static IP address), or different every time on connects, (called a dynamic IP address). In order to use a dynamic IP address, there must exist a server which can provide the address. IP addresses are usually given out through a service called DHCP or the Dynamic Host Configuration Protocol.

Internet addresses are needed not only for unique enumeration of hosted interfaces, but also for routing purposes, therefore a high fraction of them are always unused or reserved.


IP version 4 (IPv4)

IP version 6 (IPv6)