- data compression method, if any
- how the receiving device will indicate that it has received a message
There are a variety of standard protocols from which programmerscan choose. Each has particular advantages and disadvantages; for example, some are simpler than others, some are more reliable, and some are faster.
From a user's point of view, the only interesting aspect about protocols is that your computer or device must support the right ones if you want to communicate with other computers. The protocol can be implemented either in hardware or in software.