IP address
From AMule Project FAQ
An IP address is a unique value you are given when connecting to a net using the Internet Protocol.
Internally, IP addresses are 4 bytes numbers. Anyway, their common use is splitting this addresses into 1 byte numbers with a dot (.) between them. Since the range of values a 1 byte number can be is 0 - 255, the range of IP addresses goes from 0.0.0.0 to 255.255.255.255 which makes up to 2^(4*8) possible IP addresses.
Don't confuse this number with the eD2k IDs. IP addresses are to identify you anywhere in the net you are connected to, while eD2k ID's are only used to identify you on that eD2k server you are connected to.
