The book is a collection of papers concerning the theories, applications and perspectives of Variable Structure Systems (VSS), which have been a main control design methodology. The 20th century has seen the formation and consolidation of VSS theory and its applications. It has also seen an emerging trend of cross-fertilization and integration of VSS with other control and non-control areas such as feedback linearization, flatness, passivity based control, adaptive and learning control, system identification, pulse width modulation, geometric and algebraic methods, artificial intelligence, modeling and optimization, neural networks, fuzzy logic, to name just a few. To reflect these major developments in the 20th century, this book includes specially invited surveys and contributions from well-known experts in VSS as well as selected extended papers from the 6th International Workshop on VSS held on the Gold Coast, Australia 7-9 December 2000.