A cultural movement is a change in the way a number of different disciplines approach their work. This embodies all art forms, the sciences, and philosophies. Historically, different nations or regions of the world have gone through their own independent sequence of movements in culture, but as world communications have accelerated this geographical distinction has become less distinct. When cultural movements go through revolutions from one to the next, genres tend to get attacked and mixed up, and often new genres are generated and old ones fade. These changes are often reactions against the prior cultural form, which typically has grown stale and repetitive. An obsession emerges among the mainstream with the new movement, and the old one falls into neglect - sometimes it dies out entirely, but often it chugs along favored in a few disciplines and occasionally making reappearances (sometimes prefixed with "neo-").

There is continual argument over the precise definition of each of these periods, and one historian might group them differently, or choose different names or descriptions. As well, even though in many cases the popular change from one to the next can be swift and sudden, the beginning and end of movements are somewhat subjective, as the movements did not spring fresh into existence out of the blue and did not come to an abrupt end and lose total support, as would be suggested by a date range. Thus use of the term "period" is somewhat deceptive. "Period" also suggests a linearity of development, whereas it has not been uncommon for two or more distinctive cultural approaches to be active at the same time. Historians will be able to find distinctive traces of a cultural movement before its accepted beginning, and there will always be new creations in old forms. So it can be more useful to think in terms of broad "movements" that have rough beginnings and endings. Yet for historical perspective, some rough date ranges will be provided for each to indicate the "height" or accepted timespan of the movement.