This is an expensive book but worth every dollar you spend on this one. The author explains the entire ML landscape in three paragraphs – perhaps the best summary I have ever seen. It touches on Boosting, Bagging and how they can be used to improve models. Ensemble methods have become extremely popular due to the improvement in accuracy and performance. If you need a basic idea on ensembles, you may not need this book. If you want to dig deep this is a great read.