Autism is a childhood developmental disorder characterized by persistent deficits in social interaction, verbal and nonverbal communication, and by restricted, repetitive, or stereotyped behavior, interests, and activities.

It is recognized as one of the conditions in autism spectrum disorders (ASDs), which includes Asperger syndrome, which has less severe symptoms and absence of delays in cognitive development and language, childhood disintegrative disorder, marked by severe and irreversible regression of cognition, language, and motor skills typically after the age of 2 years, and pervasive developmental disorder, not otherwise specified (PDD-NOS), which is diagnosed when the full set of criteria for autism or other conditions are not met, but yet there is an impairment in the development of social and communication skills.

The signs of autism may be noted by ...