The document discusses the structure of conversations, which consists of an opening phase, topic development phase, and closing phase. The opening phase signals the start of conversation through topic initiation. The topic development phase keeps the conversation going through topic maintenance and allows speakers to shift topics. The closing phase allows speakers to end the exchange. It also discusses turn-taking systems, which involve turn-getting, turn-keeping, turn-yielding, and turn-accepting. Guidelines for casual conversations include the present speaker choosing the next or another speaker self-selecting.