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1. gearbox,
2. electrical generator,
3. yaw mechanism,
4. hydraulics system,
5. high speed shaft with its mechanical brake,
6. nacelle,
7. anemometer and wind vane. 
8. electronic controller,
9. cooling unit,
10. tower,
11. rotor blades,
12. hub,
13. low speed shaft,

Wind turbines are designed to exploit the wind energy that exists at a location. Aerodynamic modeling is used to determine the optimum tower height, control systems, number of blades{fact|April 2009} and blade shape.
Wind turbines convert wind energy to electricity for distribution. Conventional horizontal axis turbines can be divided into three components.
• The rotor component, which is approximately 20% of the wind turbine cost, includes the blades for converting wind energy to low speed rotational energy. These blades are usually made of composite fiber materials, and are increasingly being coated with specialized epoxy resins to further protect them and offer higher efficiency. 
• The generator component, which is approximately 34% of the wind turbine cost, includes the electrical generator, the control electronics, and most likely a gearbox component for converting the low speed incoming rotation to high speed rotation suitable for generating electricity. 
• The structural support component, which is approximately 15% of the wind turbine cost, includes the tower and nacelle yaw mechanism. Most of the structural components for today's turbines are made of steel and specially painted to inhibit corrosion.