The book begins with a brief overview of Arthur’s work and a proof of the correspondence between GL(n) and its inner forms in general.  Subsequent chapters develop the invariant trace formula in a form fit for applications, starting with Arthur’s proof of the basic, non-invariant trace formula, followed by a study of the non-invariance of the terms in the basic trace formula, and, finally, an in-depth look at the development of the invariant formula.  The final chapter illustrates the use of the formula by comparing it for G’ = GL(n) and its inner form G< and for functions with matching orbital integrals.