The book reviews the basic concepts and highlights the most relevant advances and developments that have taken place in the field of comprehensive two dimensional gas chromatography (GC x GC) since its introduction in 1991. The several instrumental and technical approaches assayed and developed during these seventeen years and that have contributed to the development of this powerful separation technique and to its increasing application in many areas is explained and comprehensively illustrated through a number of chapters devoted these specific topics. More specialized aspects of the technique, including theoretical aspects, modelization of the chromatographic process, software developments, and alternative couplings is also covered. Finally, special attention is paid to data treatment, for both qualitative and quantitative analysis. This book will be a practical resource that will explain from basic to specialized concepts of GC x GC and will show the current state-of-the-art and discuss future trends of this technique.