The multidisciplinary nature of tribology, the conflicting theories and approaches to it found in the literature, plus the fact that definitions of the same phenomenon often differ widely, prompted the authors to compile this work. The aim of this encyclopedia is to provide information on specific tribological terms. The entire field of tribology encompassing lubrication, friction and wear, i.e. the science and technology of interacting surfaces in relative motion, is covered. An extensive description of the chemical and biological aspects of tribology is given, including a wide range of current references and authors. The reader is also referred to relevant literature for most of the terms listed. The information presented has been made as up-to-date as possible, taking into account both the theoretical and practical nature of the subject. The encyclopedia will be an indispensable reference source in the work of engineers, chemists, physicists, metallurgists, materials and surface scientists, biotechnologists, as well as research workers in these fields.