A horizontal Axis Wind Turbine is the most common wind turbine design.
A wind turbine is a rotating machine that converts the kinetic energy of wind into mechanical energy.
The kinetic energy of an object is the extra energy which it possesses due to its motion.
If the mechanical energy is used directly by machinery, such as pumping water, cutting lumber or grinding stones, the machine is called a windmill. In physics, mechanical energy describes the sum of potential energy and kinetic energy present in the components of a mechanical system. Potential energy is energy stored within a physical system.
If the mechanical energy is instead converted to electricity, the machine is called a wind generator, wind turbine, wind power unit (WPU), wind energy converter (WEC), or aerogenerator.
In addition to being parallel to the ground, the axis of blade rotation is parallel to the wind flow. Some wind turbines are designed to operate in an upwind mode (with the blades upwind of the tower).