Kinmen, alternatively known as Quemoy, is a group of islands governed as a county by the Republic of China (Taiwan), only 10 km (6 mi) east from the city of Xiamen in Fujian, located at the southeastern coast of the People's Republic of China, from which they are separated by Xiamen Bay. Kinmen is also located 187 km (116 mi) west from the closest shoreline of the island of Taiwan across the Taiwan Strait.

The county consists of the major island of Kinmen along with several surrounding islets, as well as Wuqiu Township remotely located 133 km (83 mi) northeast from the rest of the county. Kinmen is one of two counties that constitute Fuchien Province; the other is Lienchiang County (Matsu).

Kinmen's strategic location in the Taiwan Strait has caused numerous confrontations, making it a visible embodiment of political change on cross-strait relations. In August 1958, Kinmen was heavily bombarded by the People's Liberation Army during the Second Taiwan Strait Crisis. Travel restrictions between Kinmen and the main island of Taiwan were lifted in 1994 following the end of decades-long military administration over Kinmen. A direct ferry route to Xiamen was inaugurated in January 2001 following the establishment of the Three Links.

The People's Republic of China (PRC, China) claims Kinmen as part of its own Fujian Province and considers Wuqiu to be a separate territory of Fujian apart from Kinmen itself; conversely, the ROC claims the Dadeng Islands (Tateng) as part of Kinmen, even though the PRC has effectively transferred the jurisdiction of those islands to Xiamen.

Kinmen (金門) means 'golden gate'. The name was first recorded in 1387 when the Hongwu Emperor appointed Zhou Dexing to administer the island and protect it from pirate attacks. The spelling "Kinmen" is a postal romanization. This transcription system is a variation of Nanking Syllabary, a system developed by Herbert Giles in 1892. It was adopted by the Chinese Imperial Post, part of the Chinese Maritime Customs Service led by Irishman Robert Hart. It is based on pronunciation in the Southern Mandarin, or Jianghuai, dialect. This dialect is widely spoken in Jiangsu and Anhui provinces, including the city of Nanjing. The Taiwanese Ministry of Foreign Affairs uses "Kinmen," while the United States Board on Geographic Names gives "Kinmen Island." Jinmen is the island's name both in Tongyong Pinyin and in Hanyu Pinyin. Chin-men / Chinmen is the Wade–Giles romanization of the county and island's name.

Quemoy, pronounced /kɪˈmɔɪ/ kih-MOY, is a name for the island in English and in other European languages. It may have originated as a Spanish or Portuguese transcription of the Zhangzhou Hokkien pronunciation of the name, Kim-mûi. This is the most common form of the islands' name in English. For example, works that deal with the First and Second Taiwan Strait Crises (the Quemoy Incident) and the 1960 United States presidential election debates when the islands received prominent worldwide news coverage all use the word Quemoy. In addition, the former National Kinmen Institute of Technology was renamed National Quemoy University in 2010. Kinmen scholar Wei Jian-feng advocates the use of the word Quemoy to better connect the island to "international society or achieve more recognition in the world". Kimoi is a Hokkien-derived spelling also used in the postal romanization system.

Humans have lived on Kinmen for 5,800 to 8,000 years. During the reign of Emperor Yuan (317 CE), the Five Barbarians invasion of China led six extended families to flee south and they settled in Kinmen, then called Wuzhou. More people settled there during the Tang dynasty, changing the name from Wuzhou to Kinmen.

During the Ming dynasty, more migrants settled in Kinmen. Koxinga used Kinmen as a base to capture Formosa and Penghu from the Dutch. He cut down trees to build his navy, resulting in massive deforestation that made Kinmen vulnerable to soil erosion.