For this book we have deliberately chosen that the text should follow a more or less logical design procedure for breakwaters. It follows the required design steps from the system level down to the individual crosssection level, and in time from conceptual design to construction. This systematic approach starts at the functional description of breakwaters, system analysis including side-effects and derivation of boundary conditions and continues to the actual design, first of the main armour layer and then of the rest of the cross section. It finishes with an overview of construction methods, materials and constructability issues. All existing breakwater types are discussed briefly but only the types that are frequently used all over theworld (i.e. rubble mound breakwaters, berm breakwaters and monolithic breakwaters) are treated in detail. It is expected that the reader will possess basic knowledge of hydraulic engineering. Only in some cases, where they are deemed useful for a proper understanding of the actual design process, some aspects of basic hydraulic engineering are presented.