Olives are small fruits that grow on olive trees (Olea European). They belong to a group of fruit called drupes, or stone fruits, and are related to mangoes, cherries, peaches, almonds, and pistachios. Olives are very high in vitamin E and other powerful antioxidants. They are good for the heart and may protect against osteoporosis and cancer. The healthy fats in olives are extracted to produce olive oil, which is a key component of a healthy diet.