Rice is a keystone of the grass family that produces a vast number of grains consumed by humans. It has been under intensive cultivation originating in Asia for over 4,000 years and has since spread across the world, where almost a third of the population depends on rice for vital nutrition. Rice is in the genus Oryza, which is separate from that of wheat, spelt, and similar grass crops, although it resembles them in structure.

Rice, like most grasses cultivated for human consumption, is an annual crop that needs to be resown for harvest each year. Rice is grown in partially submerged fields, also called paddies, and when mature, the plant reaches a height of approximately three feet (one meter). Rice has a classically grass-like appearance, with a small cluster of kernels at the top of a long stalk. Rice is harvested when it turns golden, and the resulting crop is threshed to remove the hulls. Many developing nations use the chaff of rice as fuel for electricity generation.

There are many cultivars of rice grown around the world, although they can primarily be broken up into long grain varieties such as jasmine and basmati and short grain styles such as those used to make sushi. If the bran, or outer part of the rice grain, is left on, the resulting rice is considered to be brown rice. If removed, the grain is white rice. Many cultures prefer brown rice because it has a higher nutritional value than white rice, including important levels of vitamin B.

Rice is a very versatile grain, which can be ground into flour for the gluten intolerant, cooked slowly in paella, or steamed to accompany a wide array of Asian dishes. Popular dishes with rice include sticky rice with mango, which uses a special type of short grain rice that comes in white, brown, and black varieties. The black variety is known in Thailand as “forbidden rice.”

Shorter grain rices tend to stick together better and are used for sushi and other dishes in which the rice needs to be shaped. Longer grain rice, such as basmati, is looser and frequently appears as a side dish. Rice is also used in the production of grain alcohols such as sake, popular in Japan.

Some white rice is sold enriched with vitamins and minerals in an attempt to provide more complete nutrition to the purchaser, especially in impoverished regions where rice is the primary staple food. Some companies have genetically modified rice in an effort to make it retain more nutrients, but these efforts have not been entirely successful.