IP: Internet protocol

envelopes and addresses the data
enables the network to read the envelope and forward the data to its destination
defines how much data can fit in a single "envelope" (a packet)

The relationship between data, IP, and networks is often compared to the relationship between a letter, its addressed envelope, and the postal system.

TCP: Transmission control Protocol

breaks data up into packets that the network can handle efficiently
verifies that all the packets arrive at their destination
"reassembles" the data