Chongqing ( ; Postal map spelling: Chungking; Wade-Giles: Ch'ung-ch'ing) is the largest and most populous of the People's Republic of China's four provincial-level municipalities, and the only one in the less densely populated western half of China. Formerly (until 14 March 1997) a sub-provincial city within Sichuan Province, the municipality of Chongqing has a registered population of 31,442,300 (2005). The boundaries of Chongqing municipality reach much further into the city's hinterland than the boundaries of the other three provincial level municipalities (Beijing, Shanghai and Tianjin), and much of the municipality, which is roughly the size of Austria, is rural. The population of the urban area of Chongqing proper was 4.1 million in 2005.

The municipal abbreviation, 渝 (Yú), was approved by the State Council on 18 April 1997. Chongqing was also a municipality of the old Republic of China. Its abbreviated name is derived from the old name of a part of the Jialing River that runs through Chongqing and feeds the Yangtze River.