Rice refers to two species (Oryza sativa and Oryza glaberrima) of grass, native to tropical and subtropical southeastern Asia and to Africa, which together provide more than one fifth of the calories consumed by humans. Rice is an annual plant, growing to 1-1.8 m tall, occasionally more, with long slender leaves 50-100 cm long and 2-2.5 cm broad. The small wind-pollinated flowers are produced in a branched arching to pendulous inflorescence 30-50 cm long. The seed is a grain (caryopsis) 5-12 mm long and 2-3 mm thick. The word rice derives from the Tamil word arisi.

Rice is a dietary staple of more than half of the world's human population (most of Asia and Latin America), making it the most consumed cereal grain. Rice cultivation is well suited to countries and regions with low labour costs and high rainfall, as it is very labour-intensive to cultivate and requires plenty of water for irrigation. However, it can be grown practically anywhere, even on steep hillsides. Rice is the world's third largest crop, behind maize (corn) and wheat. Although its species are native to South Asia and certain parts of Africa, centuries of trade and exportation has made it commonplace in many cultures.