TCP/IP

The internet uses the TCP/IP protocol. TCP/IP however is actually a suite of protocols that contains specialised protocols to allow both connected and connectionless communication over both the internet and private networks.
One of the most important protocols in the suite is Internet Protocol or IP, which is essentially a hierarchical addressing system designed to provide each network device with a unique address and a method of finding that device through the overall hierarchy.
IP is a connectionless protocol whereas TCP is a connection-orientated protocol, the A+ course does not cover TCP/IP in great depth though and concentrates on connecting client machines to existing networks.