A reservoir is a large natural or artificial lake used to store water. It is created by constructing a dam across a river or stream, which allows water to accumulate behind it. Reservoirs are essential for various purposes, including supplying drinking water, irrigation for agriculture, and generating hydroelectric power. They also help manage flood risks by controlling water flow. In addition to their practical uses, reservoirs can support local ecosystems and provide recreational opportunities. Activities such as fishing, boating, and swimming are often enjoyed in these bodies of water. Proper management of reservoirs is crucial to balance human needs with environmental health.