A few years ago, we wrote YOU: The Owner’s Manual, which taught people about the inner workings of their bodies—and how to keep them running strong. But you know what? There’s a big difference between an adult’s body and your body, between adults’ health mysteries and your health mysteries, between their questions and your questions. So, teens, this book is for YOU. We’ll talk to you about the biological changes that are happening in your brain and your body. We’ll show you how to get more energy, improve your grades, protect your skin, salvage more sleep, get fit, eat well, maximize your relationships, make decisions about sex, and so much more. In fact, in these pages, we answer hundreds of your most pressing health-related questions. And you know what else? We are going to treat you like adults in one very important way: We’re not going to preach. We’re going to give you straight-up information that you can use to make smart choices about how to live the good life—and enjoy every second of it. Starting right now.