The book is organized in three parts: the case-study tutorial, the Prototype reference, and the scr ipt.aculo.us reference. These are not references in the usual sense of the term, which generally implies a rather dry series of object and method descr iptions sprinkled with laconic snippets of code. These references are written like books unto themselves,arranged by topics, and they devote plenty of time and effort to providing background, explaining concepts, detailing the architecture,and helping you grasp the big picture as well as the details.