Strictly speaking, the Internet is a communications protocol, a language which computers use to talk to each other, called TCP/IP. This language is designed to enable computers to exchange data reliably and efficiently, though not necessarily quickly.

More generally, the term is used to signify the network of computers connected using TCP/IP: the connecting wires and the equipment used to route the information (the network infrastructure), and the computers themselves.

Even more generally, the Internet is often used to indicate the community of users and computers collectively. Though a very broad definition, this is perhaps the most useful and interesting — the Internet is really an information-based society.