If there had to be only one book about the game of chess, (openings, tactics, endings, etc.), which one would you say would be the best, the ultimate, the book to put other books to shame? Keep in mind that this book should be easy to understand for all levels of players and yet challenging enough to make you think and reason beyond your current capabilities.

There is really no book that is great for all levels, I found Reassess Your Chess exrememely helpful, but the first  time  I tried to read it( I was rated around 1300 hundred) it didn't seem very helpful and couldn't finish reading it. I picked it up a year later and everything made sense I breezed though the book and saw improvement in my game right away. When your reading a chess book you have to be at a level were your are ready to learn the material presented. One book I would recommend is Silmans Complete Endgame Course, it starts really basic and gradually builds, but it will only help you on you endgame.

I agree with the above posters. A book that's helpful for a master will be unintelligible for a beginner. Likewise, the best books for beginners are useless for masters because the concepts contained within are far too simple. Also, in my opinion the best books are ones that focus on one subject and explain it very well. Books which try to do everything end up being "jack of all trades, master of none". It would be better to ask the question this way:

What's the best book about: a) openings b) endgames c) tactics d) strategy e) thought in chess f) annotated games; for 1.beginners 2. intermediates 3. advanced players and 4. masters.

Dear,I work on a GREAT book , not expensive and quite easy to understand and follow:" Bobby Fischer teaches chess".You may find it on Amazon.com

Martine