Communication is the flow or exchange of information within people or a group of people. All living organizms communicate each other as part of their existence in this planet. It is not a patented technolgoy by human beings! Animals, plants and even microorganizms communicate each other.
To effectively communicate between two humans, there are some pre-requisites such as language, use of words or symbols in a particular pattern. A speaker may talk about a subject and different individuals may take his words in different meaning, as per their association with those words and their past experience. This is a problem in human communication. In machine to machine communication, this can be avoided. If the error rates are within limits, the receiver clearly understands the message it receives from the transmitter.