TCP-IP is a protocol suite for networking. That it was a set of rules and procedures for establishing connection over the internet with other systems. TCP handles the higher level functions like error detection, encapsulation, segmentation etc. The IP handles the datagram routing.
TCP-IP Protocol is how computers can connect to each other and the internet. The TCP (Transmission Control Protocol) is the the protocol which guarantees delivery of messages from the pc, and receives them too. The IP (Internet Protocol) is what the computers use as an addressing scheme (like a home address) its format is 4 series of numbers separated with dots, the numbers are between 0 and 255. eg, 192.168.2.1 - 192.168.2.255