Autism spectrum disorder, ASD, or autism is a mysterious disability. Doctors don't know what causes it, it's difficult to diagnose, there's no cure, and there's no universal treatment. Even though more people are diagnosed with autism today than ever before, it's difficult for many people to understand why people on the spectrum think and behave the way they do. This book serves as a guide to help teens understand the signs and symptoms of ASD, how it is diagnosed and treated, and how knowing someone with autism can change their lives. The more teens know about autism, the less mysterious it will seem.