An intensive overview of the fundamentals and physical principles on which seismic methods are based. It provides the necessary related geophysical background to understand seismic data and, hence, the reader will obtain a more clear understanding of how to properly process the data in order to ultimately obtain better seismic images that are used for accurate interpretation.With various examples, this includes the theory of elasticity, the wave equation, the types of seismic waves, single-layer reflector models, seismic events, etc.