A bean is the seed of plants in many genera of the legume family (Fabaceae) used as a vegetable for human consumption or animal feed. The seeds are sold fresh or preserved through drying (a pulse). Beans have been cultivated since the seventh millennium BCE in Thailand, and since the second millennium BCE in Europe and in Peru. Most beans, with the exception of peas, are summer crops. As legumes, the plants fix nitrogen and form seeds with a high protein content. They are produced on a scale of millions of tons annually in many countries; India is the largest producer.

Dried beans are traditionally soaked and boiled, and used in traditional dishes throughout the world including salads, soups, and stews such as chili con carne. Some are processed into tofu; others are fermented to form tempeh. Guar beans are used for their gum. The unripe seedpods of some varieties are also eaten whole as green beans or edamame (immature soybean). Some types are sprouted to form beansprouts.

Many fully ripened beans contain toxins like phytohaemagglutinin and require cooking to make them safe to eat. Many species contain indigestible oligosaccharides that produce flatulence. Beans have traditionally been seen as a food of the poor.

The word "bean" and its Germanic cognates (e.g. German Bohne) have existed in common use in West Germanic languages since before the 12th century, referring to broad beans, chickpeas, and other pod-borne seeds. This was long before the New World genus Phaseolus was known in Europe. With the Columbian exchange of domestic plants between Europe and the Americas, use of the word was extended to pod-borne seeds of Phaseolus, such as the common bean and the runner bean, and the related genus Vigna. The term has long been applied generally to seeds of similar form, such as Old World soybeans and lupins, and to the fruits or seeds of unrelated plants such as coffee beans and vanilla beans. This article discusses only legumes.

Beans in an early cultivated form were grown in Thailand from the early seventh millennium BCE, predating ceramics. Beans were deposited with the dead in ancient Egypt. Not until the second millennium BCE did cultivated, large-seeded broad beans appear in the Aegean region, Iberia, and transalpine Europe. In the Iliad (8th century BCE), there is a passing mention of beans and chickpeas cast on the threshing floor.

The oldest-known domesticated beans in the Americas were found in Guitarrero Cave, Peru, dated to around the second millennium BCE. Genetic analyses of the common bean Phaseolus show that it originated in Mesoamerica, and subsequently spread southward.

Most of the kinds of beans commonly eaten today are part of the genus Phaseolus, which originated in the Americas. The first European to encounter them was Christopher Columbus, while exploring what may have been the Bahamas, and saw them growing in fields. Five kinds of Phaseolus beans were domesticated by pre-Columbian peoples, selecting pods that did not open and scatter their seeds when ripe: common beans (P. vulgaris) grown from Chile to the northern part of the United States; lima and sieva beans (P. lunatus); and the less widely distributed teparies (P. acutifolius), scarlet runner beans (P. coccineus), and polyanthus beans.

Pre-Columbian peoples as far north as the Atlantic seaboard grew beans in the "Three Sisters" method of companion planting. The beans were interplanted with maize and squash. Beans were cultivated across Chile in Pre-Hispanic times, likely as far south as the Chiloé Archipelago.