In computer networking , an IP address ( internet protocol address ) is a unique number that devices use in order to identify and communicate with each other on a network utilizing the Internet Protocol standard. (Sometimes this is shortened to just "IP" as in "My IP is A.B.C.D".) Any participating device ó including routers, computers , time-servers, printers, internet fax machines, and some telephones ó must have its own globally unique communicable address.
IP is a network layer protocol in the internet protocol suite and is an upper layer protocol that also provides globally unique addresses (e.g., MAC address for ethernet ) but two of these addresses will not necessarily be able to communicate to each other. IP adds a service on top of these data link layer protocols ó through the use of an IP address that provides the ability to uniquely identify with and communicate with any other device on the network.
In other words, an IP address is like a full address for postal mail while a MAC address is just the house number. For example, there are many addresses with a house number of 123 but there is only one address for 123 Main Street, Anytown, California , United States . Simply mailing something to "123" will not get it there but "123 Main Street, Anytown, California, United States" is a globally unique address.
The unique nature of IP addresses makes it possible in many situations to track which computer ó and by extension, which person ó has sent a message or engaged in some other activity on the Internet. This information has been used by law enforcement authorities to identify criminal suspects; however, dynamically-assigned IP addresses can make this difficult.
Since IP addresses are not easy to remember, the Domain Name System provides the ability to map domain names (e.g. www.wikipedia.org ) to an IP address ( 207.142.131.248 ).
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