"Wikipedia Reader's Guide: The Missing Manual" gives you the essential tools for getting the most out of Wikipedia. As a supplement to "Wikipedia: The Missing Manual," this handbook provides a basic road map to the largest online collaborative encyclopedia. You'll learn the best ways to search Wikipedia for the information you need, how to navigate the encyclopedia by category, and what to do if you spot an error in an article.
This short book provides a nice overview of Wikipedia -- its history and what it is and isn't. The last part of the book gives a basic explanation of how to edit, which is still useful even though the book is 8 years old. But there's a lot more information online, and this book would have been much more useful it if had had "cheat sheets" on how to do various things.