Autism spectrum disorder (ASD) is a range of complex neurodevelopment disorders, characterized by social impairments, communication
difficulties, and restricted, repetitive, and stereotyped patterns of behavior. Autistic disorder, sometimes called autism
or classical ASD, is the most severe form of ASD, while other conditions along the spectrum include a milder form known as
Asperger syndrome, and childhood disintegrative disorder and pervasive developmental disorder not otherwise specified (usually
referred to as PDD-NOS).