L'expression faciale est un aspect important du comportement et de la communication non-verbale.
Déjà étudiée par Darwin et Duchenne de Boulogne au XIXe siècle, l'expression faciale a joué un rôle majeur dans la recherche sur les émotions depuis les travaux de Sylvan Tomkins dans les années 1960. Ses élèves Paul Ekman et Caroll Izard ont défendu l'idée d'un nombre limité d'émotions de base auxquelles sont associées des expressions faciales automatiques, universelles et innées.
L'expression faciale joue aussi un rôle important dans la langue des signes. Il est à lui seul un moyen d'expression.
The Hmong (RPA: Hmoob/Moob, IPA: [m̥ɔ̃ŋ]) are an Asian ethnic group from the mountainous regions of China, Vietnam, Laos, and Thailand. Hmong are also one of the sub-groups of the Miao ethnicity (苗族) in southern China. Hmong groups began a gradual southward migration in the 18th century due to political unrest and to find more arable land. Hmong people are known to be fiercely independent and rich in their culture, art, religion, family life and martial history, and are distinguished by costume/dress (fabric patterns represent fruit, vegetables, farming, chickens, eggs, etc.)
During the first and second Indochina Wars, France and the United States governments recruited thousands of Hmong people in Laos to fight against invading military forces from North Vietnam and communist Pathet Lao insurgents, known as the Secret War, during the Vietnam War and the Laotian Civil War. Hmong people were singled out for retribution by the Marxist Pathet Lao, and Vietnamese Army, when they took over the Laotian government in 1975, with the support of the Socialist Republic of Vietnam (SRV), and the politburo officials in Hanoi as well as the communist governments of the Soviet Union, North Korea, Cuba and China. Hundreds of thousands of Hmong refugees fled to Thailand seeking political asylum. Thousands of these refugees have resettled in Western countries since the late 1970s, mostly the United States, but also in Australia, France, French Guiana, Canada, and South America. Others have returned to Laos under United Nations-sponsored repatriation programs.