This text offers a systematic presentation of the evolution of concepts of friction, and its fundamental causes. It introduces key factors influencing friction in engineering systems. Applying these concepts, experimental observations and phenomena in various processes, readers understand the key frictional phenomena in the large-scale, commercial process of hot steel rolling. The usefulness of the book is not limited to hot rolling. It also provides an understanding of frictional phenomena in other important industrial sectors, such as automotive industry, railway transport, metal cutting and forming.