The IP ProtocolIP stands for Internet Protocol. It was designed for use on the Internet, and has become very widely adopted. You will often here it refered to as TCP/IP, which is somewhat of a misnomer because typically things which understand TCP also understand UDP. TCP and UDP are both Transport layer protocols which are transmitted using IP. IP routers route IP, regardless of what is contained in those packets (TCP, UDP, ICMP, etc).
It is not my intention or desire to go into detail about the IP protocol. If you need help in this area, I suggest you begin with TCP/IP Network Administration. You should have a general understanding of IP addresses and how (and why) IP packets are delivered. I do want to give an extensive treatment to netmasks and CIDR blocks. It is a subject which confuses a lot of people, yet it is fundamental to IP routing.