Orange juice is a liquid extract of the orange tree fruit, produced by squeezing or reaming oranges. It comes in several different varieties, including blood orange, navel oranges, valencia orange, clementine, and tangerine. As well as variations in oranges used, some varieties include differing amounts of juice vesicles, known as "pulp" in American English, and "(juicy) bits" in British English. These vesicles contain the juice of the orange and can be left in or removed during the manufacturing process. How juicy these vesicles are depend upon many factors, such as species, variety, and season. In American English, the beverage name is often abbreviated as "OJ".

An orange, also called sweet orange to distinguish it from the bitter orange, is the fruit of a tree in the family Rutaceae. Botanically, this is the hybrid Citrus × sinensis, between the pomelo and the mandarin orange. The chloroplast genome, and therefore the maternal line, is that of pomelo. The sweet orange has had its full genome sequenced.