The Internet is the ultimate example of a wide-area network. The major reason computer networks exist is for communication. Effective communication is governed by rules that are agreed upon. Communication rules for computers are called protocols and they control the formation, transport, and interpretation of data. A protocol can be defined as specifications that define procedures to follow when transmitting and receiving data.
Protocols control formatting, timing, sequence, and error checking.
Protocols can make layers of software known as protocol stacks . This stack controls Internet communication. This is Novell's transport protocol and is used to transfer data between file servers and workstations. SPX is used in environments where physical connections between computers exist. SPX guarantees delivery by having the destination node verify data reception.