According to Fruit from Spain, fruit is often categorized into six main groups: berries, pits, cores, citrus fruits, melons and tropical fruit. Valencia College explains that fruits are composed of three layers: the outermost exocarp, the mesocarp middle and the endocarp center.
Berries are small, juicy fruits with thin skins. Pits have an outerskin covering a soft, fleshy mesocarp and hard stone endocarp. Core fruits have a central core containing seeds and a thick layer of mesocarp flesh. Citrus fruits have a thick outer rind and a segmented flesh. Melons are large, juicy fruits with thick skins and many seeds. Tropical fruits are those that grow in warm climates, such as bananas, figs and avocados.