The engineering and science of interacting surfaces in relative motion is known as tribology. It studies and applies the principles of friction, wear and lubrication. Tribology is an interdisciplinary field which draws upon other disciplines such as physics, materials science, biology, engineering, chemistry and mathematics. The fundamental concepts of tribology include tribosystem, tribofilm and stribeck curve. Tribosystem is useful in providing a comprehensive assessment of the important outputs, inputs and losses to tribological systems. Tribofilms are layers which form upon surfaces that are tribologically stressed, and reduce friction and wear in the tribological systems. The stribeck curve is used to understand how the friction in fluid-lubricated contacts is a non-linear function of lubricant viscosity, contact load and entrainment velocity. The topics included in this book on tribology are of utmost significance and bound to provide incredible insights to readers. This book consists of contributions made by international experts. It will help the readers in keeping pace with the rapid changes in this field.