Interpersonal communication occurs when two people interact and attempt to mutually influence each other, usually to manage relationships. There are two main types of interpersonal communication: oral communication including verbal words and nonverbal body language, and written communication such as emails. The basic elements of interpersonal communication are a sender who sends a message, a receiver who receives it, and feedback from the receiver in response. Communication channels can be direct, with obvious and controlled delivery, or indirect, recognized subconsciously. Key principles are that interpersonal communication is inescapable, irreversible, complicated by multiple perspectives, and highly contextual based on psychological, relational, situational, environmental, and cultural factors.