Every day on TV there is the debate on who is the Greatest of All Time. On Facebook whenever anyone posts anything about LeBron, that is instantly met with hate and reminder of his Finals record. Whenever anyone posts anything about MJ, it is instantly met the lack of athleticism of the era in which he played. The truth is no one has ever defined what it means to be the Greatest of All Time. Because no one has, there is no clear answer for who it is. This book makes differing arguments for multiple players based on differing definitions. This books explores what the numbers say, accounting and adjusting for different eras. Some of the analyses are straightforward, some of them are complex, but all of the results are data driven. Along the way, I teach some statistical concepts and cover basketball advanced statistics (sabermetrics reinterpreted for basketball). I encourage differing opinions. I hope this book appeals to different readers for different reasons.