An ale is a beer made with a top fermenting yeast typically fermented between 68-75°F. Ales absorb some of the byproducts from fermentation which cause can a fruity or estery nose or flavor.  In some ale yeast strains, other compounds like phenols are produced, some of which have become an accepted part of certain beer styles such as isoamyl acetate (banana) and 4-vinyl guaiacol (clover) notable in traditional german hefeweizens.