"This book discusses "tribological interface" that consists of two solid surfaces in contact with or without fluids in between. This specific type of interface is commonly seen in reality and extremely important in engineering applications. This book is written for engineering researchers and design engineers as well as graduate and senior undergraduate students. Mathematical treatments are tailored to a first degree in engineering often without rigorous descriptions and proofs. It focuses on the basic concepts, mathematic models, numerical solution procedures, major results and their physical meanings, as well as engineering applications".