Citrus is a genus belonging to a subfamily of Rutaceae (Aurantioideae), including fruit trees better known as citrus fruits. It contains several species and innumerable varieties, some of which are subject to continuous variations, which is why there are many hybrids with particular shapes and fruits that remain on the market for relatively short times. In most cases the fruits are edible and rich in beneficial properties. Citrus plants are native to subtropical and tropical regions of Asia, Island Southeast Asia, Near Oceania, and northeastern Australia. Domestication of citrus species involved much hybridization and introgression, leaving much uncertainty about when and where domestication first happened.