城市 (chéng shì) is the standard, everyday word for a city or town in modern Chinese. It differs from 城 (chéng), which often refers to a walled city or city walls, and from 市 (shì), which is used in city names (e.g., 北京市) and also means 'market'. 都市 (dū shì) is a more formal term for a large metropolis.