This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book provides the civil engineer with practical methods to calculate the dimensions of scour holes and to furnish an introduction to the most relevant literature. It explains guidelines which can be used to solve problems related to scour in engineering practice and also reflects the main results of all the Dutch research projects directed to the phenomena of scour which have been realised in the Netherlands. The book deals with calculation methods for predicting scour near hydraulic structures. It describes some examples of scour at prototype scale. To obtain detailed information about the physical processes playing a role in scour development, many experiments in which various parameters of the flow and the scoured material were varied, were carried out by Delft Hydraulics.