Beech (Fagus) is a genus of deciduous trees in the family Fagaceae, native to temperate Europe, Asia, and North America. Recent classifications recognize between 10 and 13 species in two distinct subspecies, Engleriana and Fagus. The subgenus Engleriana, found only in East Asia, differs for its low branches, which consist of several large trunks, often with yellowish bark. The better-known Fagus subgenus beeches are highly branched with long, thick stems and smooth silver-gray bark. The European beech (Fagus sylvatica) is the most widely grown species.

Beeches are monoecious and bear both male and female flowers on the same plant. Small flowers are unisexual, female flowers are borne in pairs, male flowers are wind-pollinated catkins. They are produced in the spring, shortly after the emergence of new leaves. The fruit of the beech tree, known as the beech tree or pole, is found in small burrs that fall from the tree in autumn. They are small, roughly triangular and edible, with a bitter, astringent or mild and nut-like flavor.

The European species Fagus sylvatica yields a useful timber that is hard but dimensionally unstable. It is commonly used in furniture framing and body construction, for flooring and engineering purposes, in plywood and household items such as board, but is rarely used as a decorative wood. The timber can be used to build chalets, cottages and log cabins.

Beech wood also makes excellent firewood, splitting easily and burning for hours with bright but calm flames. Washed beech wood laths are laid at the bottom of the fermentation tanks for Budweiser (Anheuser-Busch) beer. Beech logs are burned to dry the malt used in some German smoked beers. Beech is also used to smoke Westphalian ham, andouille sausage, and some cheeses.