callers have typically learned their style from prior generations. There may or may not be some standardization of style within a region, but there is no continent-wide standardization across regions. "Revival" dances: In many cities and college towns there are dance events, open to the public, that consist primarily of Anglo-American group dances. The program may feature mainly squares, mainly contra dances, or a mixture of both. The style of squares chosen depends on the caller and may or may not conform to the local indigenous square dance style—indeed, it may be a blend of various regional styles—but it is likely to be closer to traditional than to modern western square dance. Musicians and callers typically learn not only from local mentors but also from books, recordings, and travel to and communication with other artists continent-wide; this learning process leads to a certain amount of de facto standardization. "Fun nights": Many callers conduct programs of easy dancing for people who do not square dance regularly, such as guests at a wedding or birthday party or members of a non-dance organization like a school, house of worship, or civic or social group. Such events are known in the calling trade as "fun nights", "barn dances", or "one-night stands". A caller programming such an event is likely to use a good deal of traditional dance material, even if he or she is primarily a modern Western caller. Regional styles Traditional square dances have been classified into three major types: Northeastern, Southeastern, and Western. The first two have distinctive and unique characteristics; the Western type is thought to be a blend of the two. There are many regional and local styles of square dancing; each has been adapted through the years from one or more of the three major types. Northeast The Northeastern tradition, descended from the 18th-century cotillion and the 19th-century quadrille, comprises primarily figures in which the action is initiated by a facing pair of couples, either the heads or sides. Many of the basic movements (such as "ladies chain" and "right and left") that make up the figures are common to the entire Northeastern repertoire. As in its ancestors the cotillion and quadrille, the movements in this style of square dance are synchronized with the phrases of the music. If the dancers know a particular dance by heart, they can execute it without calls, and indeed some communities that dance