The classic source of this style of beer is the Belgian "witbier" ("white beer"), of which Hoegaarden is probably the best-known example. White beer gets its name from the cloudy yeast particles which give it whitish color. Belgian white beers often have spices such as coriander or orange peel added, giving them a slightly fruity flavor.
Wheat beers have become very popular in recent years, and are especially popular in warm weather.
German Weizen (wheat) beers are a well-known variant. Hefeweizen (German for "yeast wheat") is a variety in which the yeast is not filtered out, which is similar to the Belgian variety, though Kristallweizen (clear) and Dunkelweizen (dark) varieties are also available.