The whole young pods of bean plants, if picked before the pods ripen and dry, are very tender and may be eaten cooked or raw. Thus the word "green beans" means "green" in the sense of unripe (many are in fact not green in color), as the beans inside the pods of green beans are too small to comprise a significant part of the cooked fruit.

The term "bean" originally referred to the seed of the broad bean, but was later expanded to include members of the genus Phaseolus, such as the common bean and the runner bean, and the related genus Vigna. The term is now applied in a general way to many other related plants such as soybeans, peas, lentils, kidney beans, chickpeas (garbanzos), vetches and lupins.[citation needed]

"Bean" can be used as a near-synonym of "pulse", an edible legume, though the term "pulses" is usually reserved for leguminous crops harvested for their dry grain and usually excludes crops mainly used for oil extraction (like soybeans and peanuts) or those used exclusively for sowing purposes (such as clover and alfalfa). Leguminous crops harvested green for food, such as snap peas, snow peas, etc., are classified as vegetable crops.[citation needed]

In English usage, the word "beans" is also sometimes used to mean the seeds or pods of plants that are not in the family Leguminosae, but which bear a superficial resemblance to true beans, for example coffee beans, castor beans and cocoa beans (which resemble bean seeds), and vanilla beans (which resemble the pods).[citation needed]

Beans are one of the longest-cultivated plants. Broad beans, with seeds the size of the small fingernail, were gathered in their wild state in Afghanistan and the Himalayan foothills. In a form improved from naturally occurring types, they were already being grown in Thailand since the early seventh millennium BC, predating ceramics. They were deposited with the dead in ancient Egypt. Not until the second millennium BC did cultivated, large-seeded broad beans appear in the Aegean, Iberia and transalpine Europe. In the Iliad (late 8th century) is a passing mention of beans and chickpeas cast on the threshing floor.

The common bean has been cultivated for six thousand years in the Americas.[citation needed] The oldest-known domesticated beans in the Americas were found in Guitarrero Cave, an archaeological site in Peru, and dated to around the second millennium BCE.

Beans were an important source of protein throughout Old and New World history, and still are today. There are over 4,000 cultivars of bean on record in the United States alone. An interesting modern example of the diversity of bean use is the modern urban recipe 15 bean soup, which, as the name implies, contains literally fifteen different varieties of bean.

Most of the kinds commonly eaten fresh come from the Americas, being first seen by a European when Christopher Columbus during his exploration of what may have been the Bahamas, found them being grown in fields. Five kinds of Phaseolus beans were domesticated by pre-Columbian peoples: common beans (Phaseolus vulgaris) grown from Chile to the northern part of what is now the United States, and lima and sieva beans (Phaseolus lunatus), as well as the less widely distributed teparies (Phaseolus acutifolius), scarlet runner beans (Phaseolus coccineus) and polyanthus beans (Phaseolus polyanthus) One especially famous use of beans by pre-Columbian people as far north as the Atlantic seaboard is the "Three Sisters" method of companion plant cultivation:

Dry beans come from both Old World varieties of broad beans (fava beans) and New World varieties (kidney, black, cranberry, pinto, navy/haricot).

There are many bean types, including: