Autism spectrum disorder is a complicated condition that includes problems with communication and behavior. Disorders in the part of the brain that interprets sensory input and processes language is one of its suspected causes. There are several disorders which fall under the umbrella of autism spectrum disorders such as Asperger's syndrome, autistic disorder, childhood disintegrative disorder, and pervasive developmental disorder. Autism can be diagnosed by a developmental screening test, and autism diagnostic observation schedule test. There is no cure for autism; however, some therapies and medications can be used to manage its symptoms. These therapies include behavioral and communication therapy, applied behavior analysis, occupational therapy, sensory integration therapy, and speech therapy. This book discusses the fundamentals as well as modern approaches to autism. It presents researches and studies performed by experts across the globe. This book will provide comprehensive knowledge to the readers.