Dams are barriers that restrict water flow and come in various types. The document discusses 10 major dams in Pakistan, including Mangla Dam, Tarbela Dam, and Hub Dam. It provides details on the location, construction timelines, dimensions, and purpose of these dams. Several other dams currently under construction are also mentioned, such as the Diamer-Bhasha Dam and Dasu Dam. Dams serve important purposes like irrigation, power generation, flood control, and water supply.