A counterculture is a culture whose values and norms of behavior are opposed to those of the current mainstream society, and sometimes diametrically opposed to mainstream cultural mores. A countercultural movement expresses the ethos and aspirations of a specific population during a well-defined era. When oppositional forces reach critical mass, countercultures can trigger dramatic cultural changes.
Prominent examples of countercultures in the Western world include the Levellers (1645–1650), Bohemianism (1850–1910), the more fragmentary counterculture of the Beat Generation (1944–1964), and the globalized counterculture of the 1960s which in the United States consisted primarily of Hippies and Flower Children (c. 1965–1973, peaking in 1967–1970). Regarding this last group, when referring to themselves, counterculture will usually be capitalized and is often hyphenated as: Counter-Culture or Counter-culture.