Apple is the fruit (pome) of the genus Malus belonging to the family Rosaceae, and is the most widely cultivated tree fruit. Most table apples are of the species M. domestica or hybrids of it.
The wild ancestor of Malus domestica is probably Malus sieversii (which has no common name), a tree still found wild in the mountains of central Asia in southern Kazakhstan, Kyrgyzstan, Tajikistan, and Xinjiang Province, China. Researchers are working with M. sieversii, which is resistant to many diseases and pests, in order to create hardier and more disease-resistant domestic apples.
Other species that were previously thought to have made contributions to the genome of the domestic apples are Malus baccata and Malus sylvestris, but there is no hard evidence for this.