Mansfield presents a tour of the X Window System that begins with an overview of the X system. It then covers the X server and client components and relationships; using the X system; system administration; performance factors; and writing X programs. The author strives to consolidate many topics into a single book on the X Window System. While the topics are covered, too much material is duplicated. Readers find themselves reading the same material in later sections. The organization of the book is a drawback. The author presents the material in two-page sections called modules. It appears that material was either cut or stretched to fit the two-page format. Such an arbitrary restriction on the length of material is unfortunate.