Etiquette refers to rules of behavior and customs that govern conduct in particular social situations. Email etiquette is important because written communication lacks nonverbal cues and tone can be misinterpreted, potentially damaging one's reputation. Some key tips for proper email etiquette include keeping messages brief, using a professional tone and language, responding promptly, avoiding angry emails, and being clear about the purpose and audience for any message. Proper email etiquette helps ensure effective and appropriate communication.