Communication is the operation, which (re-)produces social systems, it is the central lastelement (specific operation) for the definition and the retention of society. A change of communicative possibilities by a new medium also changes society.
Communication is a synthesis of three components: message, information and understanding: communication comes into being, when its understood that an information is imparted.
In the social dimension these components are ascribed to at least two abstracted persom. Person a (= ego), who understands, and person b (= alter), who imparts. The imparted information can't be identical to the understood information.