Earthquakes are one of the most feared natural disasters. Thus the need to understand their origin and prediction wil be useful in building code structures and code development. Plate Tectonics theory and its implications in occurence of earthquakes are described. Recent history of earthquakes is reviewed. Earthquake terminologies such as fault, strike, and dip, thrust faults, magnitude, fault rupture and others are explained.. Measures to estimate the potential occurence of an earthquake are discussed briefly.