A scientific look at the skill of juggling. In this book, we look at all the things that limit jugglers and make the skill so challenging. Topics covered in the book include: juggling definitions, a brief history of juggling, juggling records, different juggling patterns and their pros and cons, Shannon's juggling theorem, physics of thrown objects and useful equations, good form, throwing error, ideal patterns, how to avoid collisions, optimizing juggling, the human limits of juggling, changing the constraints, learning to juggling, overview of "siteswap" notation, and training advice.