Internet protocol, or IP address, is a unique number (like a phone number) that is given to you by your service provider. Most users retain their IP address for the lifetime of the contract with thier isp, although some companies (AOL and it's subsidiaries) give out dynamic IP addresses. When an AOL user logs on, they are allocated a random IP from the pool of free ones. Since AOL is huge, and not all of it's customers are online at once, it saved on IP's buy getting less than it had customers. IP's can be hidden by subnet masks, proxy servers or ciphers.
The format of the IP is four numbers of 1-3 digits, separted by full stops.
127.0.0.1 is the address that your computer uses to refer to itself.
220.127.116.11, 18.104.22.168, 22.214.171.124