How does a person's communication style change based on whom they are interacting with?

A persons communication style will change based on the person they are talking to. When talking to someone familiar to us such as a friend or family member our communication takes on a casual style since we know said person where as when we talk to someone we are not quite familiar with such as a co-worker, our boss, someone we talk to at a front desk we are more polite and may keep to ourselves. The things we say and don't say are determined by who we are talking to and what we are talking about.