An oasis is a spring or waterhole situated in a hot desert. Oases have many benefits: they provide water for people living in desert regions and allow food plants like date palms, figs, olives and apricots to be grown. They also provide shade, which is often hard to find in deserts.

Oases are formed when underground streams or rivers flow to the deserts surface. In most parts of the world, there is water underground, which we call the 'water table'. Even in deserts this water table is present. It is possible to dig a well in order to reach the water table, but sometimes it can be kilometres underground. In some places (usually at low altitudes) it is possible for the watertable to reach the earth's surface. When this happens, an oasis is formed. Oases are especially likely to form along the few rivers that may flow through deserts.

Most towns and villages in deserts are located in or around an oasis. Some nomadic desert tribes, like the Bedouin, will live in tents and move from oasis to oasis, travelling at night to escape the day's heat. People who live in oases make excellent use out of every scrape of fertile land. They even provide enough water for people to keep cattle, sheep and goats.