A counterculture is a culture whose values and norms of behavior differ substantially from those of mainstream society, 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 Non-conformists of the 1930s, the more fragmentary counterculture of the Beat Generation (1944–1964), followed by the globalized counterculture of the 1960s (1964–1974), usually associated with the hippie subculture as well as the diversified punk subculture of the 1970s and 1980s.
