Well, for two computers to communicate with one another, an agreed-upon standard (protocol) is necessary. In the early days there were various ideas about what information needed to be sent across the wire, in what order. The BSD unix operating system proposed some ideas for this, which I believe formed the first version of TCP/IP. Eventually more groups using ARPANET (the predecessor to the Internet) also implemented TCP/IP in their work, and it became a standard.
