The tangerine (Citrus Ã— tangerina) is an orange-coloured citrus fruit. It is a variety of the Mandarin orange (Citrus reticulata). Tangerines are smaller than most oranges, and the skin of some varieties will peel off more easily. The taste is often less sour, or tart, than that of an orange. Good quality tangerines will be firm to slightly soft, heavy for their size, and pebbly-skinned with no deep grooves, as well as orange in color. Peak tangerine season is short, lasting from November to January in the Northern Hemisphere. Tangerines are most commonly peeled and eaten out of hand. The fresh fruit is also used in salads, desserts and main dishes. Fresh tangerine juice and frozen juice concentrate are commonly available in the United States. The number of seeds in each segment (carpel) varies greatly. A popular alternative to tangerines are clementines, which are also a variant of the mandarin orange. An oil is a substance that is in a viscous liquid state ("oily") at ambient temperatures or slightly warmer, and is both hydrophobic (immiscible with water) and lipophilic (miscible with other oils, literally). This general definition includes compound classes with otherwise unrelated chemical structures, properties, and uses, including vegetable oils, petrochemical oils, and volatile essential oils. Oil is a nonpolar substance.