A wind turbine is a machine that converts renewable kinetic energy in wind into rotary mechanical energy.  This rotational energy is then converted into electricity, by the use of a generator.  The wind turbine is somtimes called a wind generator, wind power unit, wind energy converter, or aerogenerator.

A wind turbine consists of three basic parts: the tower, the nacelle (housing), and the rotor blades.  The wind turbine tower is either a steel lattice tower similar to electrical towers or a steel tubular tower.  Wind turbines also include a grid tie inverter to connect to an electrical transmission system.

Wind turbines can be separated into two types based by the axis in which the turbine rotates. Turbines that rotate around a horizontal axis are more common. Vertical-axis wind turbines are used less frequently.

Horizontal-axis wind turbines have the main rotor shaft and electrical generator at the top of a tower, and must be pointed into the wind.  Small turbines are pointed by a simple wind vane, while large turbines use a wind sensor coupled with a servo motor.  Most have a gearbox, which turns the slow rotation of the blades into a faster rotation that is more suitable to drive an electrical generator.

Wind turbines used in wind farms for commercial production of renewable electric power are usually three-bladed and pointed into the wind by computer controlled servo motors.  These have high tip speeds of up to six times the wind speed, high efficiency, and low torque ripple, which contribute to good reliability. The blades range in length from 20 to 40 metres (65 to 130 ft) or more.  The tubular steel towers range from 60 to 90 metres (200 to 300 feet) tall.  The blades rotate at 10 to 22 revolutions per minute.