A wind turbine is a rotating machine which converts the kinetic energy in wind into mechanical energy. If the mechanical energy is used directly by machinery, such as a pump or grinding stones, the machine is usually called a windmill. If the mechanical energy is then converted to electricity, the machine is called a wind generator, wind turbine, wind power unit (WPU), wind energy converter (WEC), or aerogenerator.

This article discusses wind electric power generation machinery. The Windmill article discusses machines used for grain-grinding, water pumping, etc. The article on wind power describes turbine placement, economics and public concerns. The wind energy section of that article describes the distribution of wind energy over time, and how that affects wind-turbine design.