A truffle is the fruiting body of a subterranean ascomycete fungus, predominantly one of the many species of the genus Tuber. In addition to Tuber, over one hundred other genera of fungi are classified as truffles including Geopora, Peziza, Choiromyces, and Leucangium. These genera belong to the class Pezizomycetes and the Pezizales order. Several truffle-like basidiomycetes are excluded from Pezizales, including Rhizopogon and Glomus. Truffles are ectomycorrhizal fungi, so they are usually found in close association with tree roots. Spore dispersal is accomplished through fungivores, animals that eat fungi. These fungi have significant ecological roles in nutrient cycling and drought tolerance.

Some truffle species are highly prized as food. French gastronome Jean Anthelme Brillat-Savarin called truffles "the diamond of the kitchen". Edible truffles are used in Italian, French and numerous other national haute cuisines. Truffles are cultivated and harvested from natural environments.