The document discusses different types of dams. It defines a dam as a structure built across a stream, river, or estuary to store water, creating a reservoir for uses like water supply, irrigation, or power generation. It describes the main components of dams like spillways. It classifies dams based on size, use, and structure. The main structures discussed are embankment, arch, gravity, and timber dams. Important dams mentioned include Kaptai Dam in Bangladesh, Hoover Dam in the US, Aswan Dam in Egypt, Nurek Dam in Tajikistan, Glen Canyon Dam in the US, and Three Gorges Dam in China.