Vietnam (Vietnamese: Việt Nam, [vîət nāːm] (listen), commonly abbreviated VN), officially the Socialist Republic of Vietnam (SRV), is a country in Southeast Asia. It is located at the eastern edge of mainland Southeast Asia, with an area of 331,212 square kilometres (127,882 sq mi) and population of 99 million, making it the world's fifteenth-most populous country. Vietnam borders China to the north, and Laos and Cambodia to the west. It shares maritime borders with Thailand through the Gulf of Thailand, and the Philippines, Indonesia, and Malaysia through the South China Sea. Its capital is Hanoi and its largest city is Ho Chi Minh City (commonly referred to by its former name, Saigon).

Vietnam was inhabited by the Paleolithic age, with states established in the first millennium BC on the Red River Delta in modern-day northern Vietnam. The Han dynasty annexed Northern and Central Vietnam under Chinese rule from 111 BC, until the first dynasty emerged in 939. Successive monarchical dynasties absorbed Chinese influences through Confucianism and Buddhism, and expanded southward to the Mekong Delta, conquering Champa. The Nguyễn—the last imperial dynasty—surrendered to France in 1883. Following the August Revolution, the nationalist coalition Viet Minh under the leadership of communist revolutionary Ho Chi Minh proclaimed independence of Vietnam in 1945.

Vietnam went through prolonged warfare in the 20th century. After World War II, France returned to reclaim colonial power in the First Indochina War, from which Vietnam emerged victorious in 1954. As a result of the treaties signed between the Viet Minh and France, Vietnam was also separated into two parts. The Vietnam War began shortly after, between the communist North, supported by the Soviet Union and China, and the anti-communist South, supported by the United States. Upon the North Vietnamese victory in 1975, Vietnam reunified as a unitary socialist state under the Communist Party of Vietnam (CPV) in 1976. An ineffective planned economy, a trade embargo by the West, and wars with Cambodia and China crippled the country further. In 1986, the CPV initiated economic and political reforms similar to the Chinese economic reform, transforming the country to a market-oriented economy. The reforms facilitated Vietnamese reintegration into the global economy and politics.

A developing country with a lower-middle-income economy, Vietnam is nonetheless one of the fastest-growing economies of the 21st century, with a GDP predicted to rival developed nations by 2050. Vietnam has high levels of corruption and censorship and a poor human rights record; the country ranks among the lowest in international measurements of civil liberties, freedom of the press, and freedom of religion and ethnic minorities. It is part of international and intergovernmental institutions including the ASEAN, the APEC, the CPTPP, the Non-Aligned Movement, the OIF, and the WTO. It has assumed a seat on the United Nations Security Council twice.