Soybeans are a legume which have been cultivated by the Chinese for thousands of years. They are so important to the Chinese that they're considered one of the five sacred grains (the others are rice, wheat, barley and millet). The Japanese have been growing soybeans since the 6th century, but the Europeans only since the 17th. Today 90% of soybeans are used to feed livestock.

Soybeans are notable for their very high nutritive value, which wasn't proven scientifically until the 20th century, and since then they have become an important crop in North America, where they grow easily.

There are more than 1,000 varieties of soybean, ranging in size from as small as a pea to as large as a cherry. The pods can be tan to black, and are covered with fuzz. The beans can be red, yellow, green, brown and black, or a combination of colours. Their flavour is bland, though the husks can be bitter, so the beans are often hulled. Unlike other legumes, however, they are low in carbohydrates and high in protein and "good" oil.

Soybeans are used to produce tofu, a cooking oil, a flour, soy milk, soy sauce, miso, tamari sauce, and black bean sauce. They can be soaked and cooked like any other dried bean, and can sprouted and used in salads. Soybean by-products are used to make margarine and as an emulsifier in processed foods as well as nonfood items like soap and plastic.