"The family of Musielak-Orlicz (M-O) spaces mentioned in the title includes not only those of classical Lebesgue and Orlicz type, but also the spaces with variable exponent that have attracted such a great deal of interest in recent years. After a preparatory chapter in which basic facts are established, a detailed study is made of M-O spaces, following which Sobolev spaces based on them are examined. Finally, there is a chapter giving applications, dealing in particularwith the variable exponent p Laplacian.A particular virtue of the book is that the unified approach adopted to deal with very general circumstances is accomplished by keeping the technicalities firmly subordinate to the main ideas. It is a welcome addition to the number of books dealing with related topics and should be of definite interest to many."-Professor David Edmunds, University of Sussex