The document discusses netiquette, which is the code of proper behavior for communicating on the internet. It is important to know netiquette because online communication is fast and messages can be misunderstood without context clues like tone of voice. The document provides eight rules of netiquette, such as avoiding all capital letters, filling in subject lines, being careful what is sent to avoid spreading viruses or spamming others, and keeping business communication professional. Following the rules of netiquette can help avoid misunderstandings in online communication.