Interpersonal communication happens in a number of ways, including verbal and nonverbal transference of information. The information we transmit can be translated differently according to the context. The surface level of a message is called its "content message," while the way it is said refers to its "relationship message." For example, if you said "I'm so glad you're here," the content message would imply that you were happy to see the person. If you said it in a sarcastic tone of voice, however, the relationship message would mean something completely different.
According to William Schutz, interpersonal communication happens because we need a variety of things from other people.