Protocols are conventions that facilitate intercomputer communications. Simply put, protocols are agreed-on formats for transmitting data at the bit and byte level between two computing devices. Protocols determine how data will be compressed and sent, what kind of error checking will be used, how the sending device will indicate completion of send, and how the receiving device will indicate reception of the message. Protocols are an intrinsic aspect of data communications across networks. A range of standard protocols varying from highly reliable, to highly efficient, to speedy, currently exist and offer a diversity of communications options. Choosing protocols for data communications is greatly facilitated these days by the range available. An essential aspect of this choice is that both computing devices seeking to be in communication must support the protocols used, which can be implemented either in hardware or in software.

The Open Systems Interconnect (OSI) Reference Model...