First of all, I want to thank my lovely girlfriend for supporting me along the way of this journey. I know for sure that this would have not been possible without her, and I will be always grateful to her.

I also thank my friends, Gabriel Garcia and Tasos Bitsios, who where there answering my questions and sharing with me their thoughts about the book, chapters, and the code. Last but not least, I want to thank all the reviewers who helped me with their comments, specially Brent Shaffer for his patience and help on the implementation of OAuth 2.0 and for letting me use his library in this book.

I want to mention some people who, over the years, have contributed somehow to the person I am today and have encouraged me to follow my dreams, keep exploring new stuff, pursue new challenges, and supported me with all my crazy ideas. My parents Vicente Vallés Serrat and Manuela Ramos González, my brother Bryan Vallés Ramos, my first boss Òscar Martínez Ciuró, and Stuart Helen Overton-Smith for getting on the plane with me, teaching me how to fly, and helping me accomplish my dream of being a pilot. A special mention goes for my cats, Schrödinger and Bones, for giving me company and staying with me at 4 a.m. while I was writing.

Finally, I also want to thank all the people who made efforts and invested time researching the polyphasic sleep cycles and shared their knowledge for free on the Internet. To write this book, I switched to everyman sleep cycle that allowed me to stay awake 19 hours per day for the last six months.