This is a superlative book for club and class players, buy it now (4th edition). If you have reached the master range without reading this book, you probably know the material intuitively, but borrow it and make sure. If you are a beginner, but really enjoy chess, put this book on your wish list.
Silman teaches a chess planning method in this book based on assessing the differences in the position between the players. He uses the term imbalances to refer to these differences. He covers both static imbalances like pawn structure or material imbalances and dynamic imbalances like initiative and development.
You are to develop your plan around enhancing the value of your favorable imbalances or converting an imbalance into another more favorable imbalance. For instance, if you have a lead in development and the initiative, you should try to convert that into a static imbalance like a material advantage. Your plan should also work against your opponent's natural plan by minimizing negative imbalances.
For me, the part on minor pieces in the middlegame which deals with creating, using and converting a superior minor piece was worth the price of the book. There were eleven other useful parts with multiple chapters, each.
I know I will be rereading this book, again and again, as I gain better understanding.
His list of imbalances:
- Superior minor piece
- Pawn Structure
- Control of a key file or square
- Lead in development