Vietnamese is a Viet–Muong language that originated in the north of modern-day Vietnam, where it is the national and official language. It is the native language of the Vietnamese (Kinh) people, as well as a first or second language for the many ethnic minorities of Vietnam. As the result of Vietnamese emigration and cultural influence, Vietnamese speakers are found throughout the world, notably in East and Southeast Asia, North America, Australia and Western Europe. Vietnamese has also been officially recognized as a minority language in the Czech Republic.

Vietnamese is the sole official and national language of Vietnam. It is the first language of the majority of the Vietnamese population, as well as a first or second language for the country's ethnic minority groups.

In the Czech Republic, Vietnamese has been recognized as one of 14 minority languages, on the basis of communities that have resided in the country either traditionally or on a long-term basis. This status grants Czech citizens from the Vietnamese community the right to use Vietnamese with public authorities and at courts anywhere in the country. Moreover, it also grants the use of Vietnamese in public signage, election information, cultural institutions, and access to legal information and assistance in municipalities where at least 10% of the population is of the minority group.

It is part of the Austroasiatic language family of which it has by far the most speakers (several times as many as the other Austroasiatic languages combined). Vietnamese vocabulary has borrowings from Chinese, and it formerly used a modified set of Chinese characters called chữ nôm given vernacular pronunciation. The Vietnamese alphabet (chữ quốc ngữ) in use today is a Latin alphabet with additional diacritics for tones and  certain letters.

As the national language, Vietnamese is spoken throughout Vietnam by ethnic Vietnamese and by Vietnam's many minorities. Vietnamese is also the native language of the Gin minority group in southern Guangxi Province in China. A significant number of native speakers also reside in neighboring Cambodia and Laos.

In the United States, Vietnamese is the fifth most spoken language, with over 1.5 million speakers, who are concentrated in a handful of states. It is the third most spoken language in Texas and Washington; fourth in Georgia, Louisiana, and Virginia; and fifth in Arkansas and California. Vietnamese is the seventh most spoken language in Australia. In France, it is the most spoken Asian language and the eighth most spoken immigrant language at home.