The TCP/IP model has four layers: application, host-to-host layer, internet layer and network access layer.
TCP is the transmission protocol that is used and it is connection-oriented.
IP stands for Internet.
A stream of bytes is broken into segments and reconnected at the other end. The packets are retransmitted whatever is lost and the segments are organized might in the correct order.
The boom of new different applications that should be interoperable motivates engineers to make tcp/ip packets more independent.