The document provides information about hydroelectric power plants including definitions, basic principles, components, and functions. It discusses:
1) Hydroelectric power plants generate electricity by harnessing the potential energy of water stored at high elevations and converting it through a turbine into electrical energy.
2) Key components include a dam to store water, penstocks to channel water to turbines, and a generator driven by the turbine to produce electricity.
3) The selection of a suitable site considers factors like adequate water supply, terrain for water storage, transportation access, and proximity to energy demand centers.