You are many things. You are miles of blood vessels, hundreds of muscles, many thousands of hairs. You are a furnace, filters, and a fancy computer with a huge memory bank. You are a finely tuned organism with more parts than there are people in New York City. When you think about it, you’re pretty incredible. This is a book to help you explore the amazing territory that is inside the bag you live in that you call your skin. It will show you experiments to try, tests to take, and tools to make that will help you see and feel and hear what is going on inside. You’ll amaze yourself.