Why is a communication protocol important?

Unless we have an ageement between the two communicating parties information may get lost or miscommunicated. This agreement is the protocol. Communications protocols usually have a number of parts e.g. Handshake, encoding method, compressions methods, packet / frame structure, addressing etc. Anyone can write a protocol, but in order for it to be useful, people (systems) must use it widely. This is why protocols are often defined by standards bodies, but some protocols e.g. SSL can be used widely even though they are not specifically from a standards body. In short - if we don't have a protcols we won't be able to communicate between different devices.