Macau (/məˈkaʊ/; traditional Chinese: 澳門; simplified Chinese: 澳門; pinyin: Àomén), also spelled Macao, is one of the two Special Administrative Regions of the People's Republic of China, the other being Hong Kong. Macau lies on the western side of the Pearl River Delta across from Hong Kong to the east, bordered by Guangdong Province to the north and facing the South China Sea to the east and south.[8] The territory's economy is heavily dependent on gambling and tourism, but also includes manufacturing. The Cantonese people from Hong Kong and Guangdong, especially recent mainland tourism from Mandarin-speaking regions, have boosted the economy of Macau significantly.

A former Portuguese colony, Macau was administered by Portugal from the mid-16th century until late 1999, when it was the last remaining European colony in Asia.[9][10] Portuguese traders first settled in Macau in the 1550s. In 1557, Macau was rented to Portugal by the Chinese empire as a trading port. The Portuguese administered the city under Chinese authority and sovereignty until 1887, when Macau became a colony of the Portuguese empire. Sovereignty over Macau was transferred back to China on 20 December 1999. The Sino-Portuguese Joint Declaration and the Basic Law of Macau stipulate that Macau operate with a high degree of autonomy until at least 2049, fifty years after the transfer.[11] By 2002, it had become one of the world's richest cities.[12] It became the world's biggest gambling centre in 2006.[13]

Under the policy of "one country, two systems", the PRC's Central People's Government is responsible for the territory's defense and foreign affairs, while Macau maintains its own legal system, police force, monetary system, customs policy, and immigration policy. Macau participates in many international organizations and events that do not require members to possess national sovereignty.[11][14]

According to The World Factbook, Macau has the second highest life expectancy in the world.[15] In addition, Macau is one of the very few regions in Asia with a "very high Human Development Index", ranking 23rd or 24th in the world in 2007 (with Japan being the highest in Asia; the other Asian countries/regions within the "very high HDI" category are South Korea, Taiwan, Hong Kong, Singapore, and Brunei).