We communicate with each other to inform, to instruct, to persuade, to amuse, to annoy. Informing and instructing aim to alter the receiver's concepts, whereas persuading, amusing or annoying aim to change his preferences or feelings. In a work situation people do make jokes and enemies, and use the arts of persuasion, but much of their communication has an informal or instructional aspect.

p. 1. - Information Systems (1973)