Autistic spectrum disorder (ASD) is a set of neurodevelopmental disorders that cover the lifespan. It occurs earlier than the other disorders in this group and is evident before the age of three years. This disorder involves three areas of abnormality; impaired social interaction (failure to develop peer relationship, no eye contact or other nonverbal interactive behaviors, no seeking to share enjoyment with others, or lack of social responses), impaired communication (delay or lack of language, stereotyped language, repetition of words said by others, or lack of imaginative play), and stereotyped behavior (inflexibility, preoccupation with odd interests, strict adherence to nonfunctional routines, or repetitive mannerisms such as hand flapping or head banging).