Commonly referred to as string beans, the string that once was their trademark (running lengthwise down the seam of the pod) can seldom be found in modern varieties. It's for this reason (the breeding out of the "string") that string beans are often referred to as "snap beans." Because they are picked at a younger, immature stage, "snap beans" can literally be snapped in half with a simple twist of the fingers. Although these bright green and crunchy beans are available at your local market throughout the year, they are in season from summer through early fall when they are at their best and the least expensive. You may also see them referred to as "haricot vert"—this term simply means "green bean" in French and is the common French term for this vegetable. This term can also refer to specific varieties of green beans that are popular in French cuisine because of their very thin shape and very tender texture
Green beans belong to the same family as shell beans, such as pinto beans, black beans, and kidney beans. In fact, all of these beans have the exact same genus/species name in science—Phaseolus vulgaris—and all can be referred to simply as "common beans." However, since green beans are usually picked while still immature and while the inner beans are just beginning to form in the pod, they are typically eaten in fresh (versus dried) form, pod and all. Green beans are often deep emerald green in color and come to a slight point at either end. Green bean varieties of this common bean family are usually selected for their great texture and flavor while still young and fresh on the vine. In contrast, dried bean varieties like pinto or black or kidney beans are usually selected for their ability to produce larger and more dense beans during the full time period when they mature on the vine. At full maturity, their pods are often too thick and fibrous to be readily enjoyed in fresh form, but the beans inside their pods are perfect for drying and storing.