Generation of electrical energy from wind can be economically achieved only where a significant wind resource exists. Because of the cubic relationship between wind velocity and output energy, sites with small percentage differences in average wind speeds can have substantial differences in available energy. Therefore, accurate and thorough monitoring of wind resource at potential sites is a critical factor in the siting of wind turbines. An accurately measured wind-speed frequency spectrum at a site is another important factor. For assessment of the wind-power potential of a site, most investigators have used simple wind-speed distributions that are parametrized solely by the arithmetic mean of the wind speed. Assessment of power output of a wind turbine will be accurate if the wind speeds measured at the hub height (30-50 m) of a wind turbine-generator are known. However, the existing wind data available at most of the meteorological stations worldwide is measured at a height of 10 or 20 m above the ground. Therefore, wind speeds measured at anemometer heights are extrapolated to the hub height of the wind turbine. Many investigators have proposed simple expressions for height extrapolation of wind speeds. This paper reviews wind-speed prediction and forecasting, and development of techniques for accurate assessment of wind-power potential. Also, the need of wind-resource assessment and the techniques and methods used for it are highlighted.