Ales are brewed with "top-fermenting" yeasts at temperatures in the region of 10 to 21 °C (room temperatures). Ales cover the broadest range of beer styles including bitters, pale ales, porters, stouts, barley wines, trappist, lambic, and alt. The British Isles are famous for their ales, and it is a popular style with home brewers and micro-breweries.

Source : FAQ of alt.drinks.beer