A revised and expanded second edition of Reiter's classic text, this book deals with various developments in analysis centring around the fundamental work of Wiener, Carleman, and Weil. It starts with the classical theory of Fourier transforms in euclidean space, continues with a study of certain general function algebras, and then discusses functions defined on locally compact groups. The book gives a systematic introduction to these topics and endeavours to provide tools for further research. The new edition contains relevent material that was unavailable when the first edition was published.