Autism Spectrum Disorder (ASD) is a lifelong disorder that impairs an individual's understanding of what he or she sees, hears or otherwise senses. It is a disorder that is characterized by impaired development in communication, social interaction, and behavior. It is found in every country and region of the world, and in families of all racial, ethnic, religious, and economic backgrounds. Ongoing research around the world has still not unearthed a definitive conclusion on the causes of Autism. What is evident though is that Autism is neurological in origin and the genetic component factors in its occurrence.

The classification of autism occurred in 1943, when psychiatrist Dr. Leo Kanner who reported on 11 children with striking behavioural similarities, and introduced the label "early infantile autism". He pointed to "autistic aloneness" as one of its main features, which is a description of the mental isolation of an individual accompanied by an obsessive insistence on sameness. He suggested "autism" from the Greek avtoc, (autos), meaning 'self', to describe the fact that the children seemed to lack interest in other people' (in Frith, 1989, p.10-11).

Lorna Wing & Judith Gould (1979) gave the triad of impairment as the diagnostic criteria for autism Impaired ability to communicate
Impaired ability to socialize
Impaired imagination

Kellman defines autism as "a little understood disorder that appears to be either genetic in origin, or perhaps the result of damage during or before birth… a part of a long continuum that includes, at one extreme, severely retarded, mute individual, beset by numerous, compulsive, tic-like behaviours and at the other, highly articulate, single-minded geniuses with adequate social skills and a marked inability to take part in the mutual communicative aspects of social existence" (1999. pg.262).

Autism may have an onset in infancy yet not be recognized until some time later Retrospective parental reports suggest that many children with autism have had significant delays in the development of motor abilities, speech, verbal or non-verbal communication, reasoning and learning skills, social interactions and abnormal responses to sensations (Baron-Cohen, 1995; Frith, 1989; Hobson, 1993). According to Simon Baron-Cohen, the source of this disability lies in the fact that people with autism suffer from "mindblindness" hence are blind to their own and to other people's minds which is why they experience difficulty in communication, interaction and imagination (Baron-Cohen, 2000).

It is estimated to affect nearly 2 million individuals in India (T C Daley and Sigman, 2002). The incidence of ASD is said to be 2 to 6 in 1000 (CDC-USA), making it the third most prevalent developmental disorder in the world. The incidence of Autism is higher than disabilities like Cerebral Palsy or Down’s syndrome.