This book is for people who know that it would be a pretty good idea to learn the language, but aren't 100% sure why. You've heard the hype, but haven't seen enough substance to figure out what XML is, and what it can do. You may already be somehow involved in web development, and probably even know the basics of HTML, although neither of these qualifications is absolutely necessary for this book.
What you don't need is knowledge of SGML (XML's predecessor), or even markup languages in general. This book assumes that you're new to the concept of markup languages, and we have tried to structure it in a way that will make sense to the beginner, and yet quickly bring you to XML expert status.
The word "Beginning" in the title refers to the style of the book, rather than the reader's experience level. There are two types of beginner for whom this book will be ideal:
Programmers who are already familiar with some web programming or data exchange techniques. You will already be used to some of the concepts discussed here, but will learn how you can incorporate XML technologies to enhance those solutions you currently develop.
Those working in a programming environment but with no substantial knowledge or experience of web development or data exchange applications. As well as learning how XML technologies can be applied to such applications, you will be introduced to some new concepts to help you understand how such systems work.