County is the standard English translation of Xián or formally County level divisions. In the People's Republic of China, counties are found in the third level of the administrative hierarchy in Provinces and Autonomous regions, and the 2nd level in municipalities and Hainan province, a level that is known as "county level" and also contains autonomous counties, county-level cities, banners, autonomous banners, and City districts. There are 1,464 counties in mainland China out of a total of 2,862 county-level divisions. Xian have existed since the Warring States Period, and were established nationwide during the Qin Dynasty.

In Imperial China, the county was a significant administrative unit because it marked the lowest level of the imperial bureaucratic structure — in other words, it was the lowest level that the government reached. Government below the county level was often undertaken through informal non-bureaucratic means, varying between dynasties. The head of a county was the magistrate, who oversaw both the day-to-day operations of the county as well as civil and criminal cases.

Autonomous counties are a special class of counties in mainland China reserved for non-Han Chinese ethnic minorities. Autonomous counties are found all over China, and are given, by law, more legislative power than regular counties. There are 117 autonomous counties in mainland China.