Peer education is information exchange and sharing based on peer relationship. Peer education can be divided into formal and informal. Informal peer education may happen at any time, but the purpose is not very clear and there is no known educational goal in advance. Informal peer education can take place anywhere people feel convenient, such as offices, dormitories, workshops, communities, and even streets. Formal peer education, with clear goals and strict design and organization, is becoming an educational intervention method based on interpersonal communication in health education and promotion projects.