Green beans are young, unripe fruits of various cultivars of the common bean (Phaseolus vulgaris), although immature or young pods of the runner bean (Phaseolus coccineus), yardlong bean (Vigna unguiculata subsp. sesquipedalis), and hyacinth bean (Lablab purpureus) are used in a similar way. Green beans are known by many common names, including French beans (French: haricot vert), string beans (although most modern varieties are "stringless"), and snap beans or simply "snaps." In the Philippines, they are also known as "Baguio beans" or "habichuelas" to distinguish them from yardlong beans.

They are distinguished from the many other varieties of beans in that green beans are harvested and consumed with their enclosing pods before the bean seeds inside have fully matured. An analogous practice is the harvest and consumption of unripened pea pods, as is done with snow peas or sugar snap peas.