The credit goes to my coauthor, Holden Karau, the reviewers, and the editors at Packt Publishing. Holden wrote the first edition, and I hope I was able to contribute to the same depth. I am deeply thankful to the reviewers Lijie, Robin, and Toni. They spent time diligently reviewing the material and code. They have added lots of insightful tips to the text, which I have gratefully included. In addition, their sharp eyes caught tons of errors in the code and text. Thanks to Arvind Koul, who has been the chief force behind the book. A great editor is absolutely essential for the completion of a book, and I was lucky to have Arvind. I also want to thank the editors at Packt Publishing: Anila, Madhunikita, Milton, Neha, and Shaon, with whom I had the fortune to work with at various stages. The guidance and wisdom from Joe Matarese, my boss at http://www.blackarrow.tv/, and from Paco Nathan at Databricks are invaluable. My spouse, Usha and son Kaushik, were always with me, cheering me on for any endeavor that I embark upon—mostly successful, like this book, and occasionally foolhardy efforts! I dedicate this book to my mom, who unfortunately passed away last month; she was always proud to see her eldest son as an author.