Autism is a developmental disability that affects, often severely, a person's ability to communicate and socially interact with others. It is four times more prevalent in males than females.

Currently, autism is believed to affect 1 in every 166 people. The rate of people being diagnosed with autism has increased substantially over the past two decades.  Although this may be in part due to improved diagnostic techniques and to changes in the criteria for autism spectrum disorders (see below), the majority of experts agree these changes are not enough to explain the epidemic rates at which autism is being diagnosed. 

Autism Spectrum Disorders is an umbrella term that includes classic autism (also known as Kanner's autism or Kanner's syndrome), Asperger's syndrome, and pervasive developmental disorder (PDD). Autism is considered a spectrum disorder because the number and intensity of the symptoms people with autism display may vary widely. However, all people with autism demonstrate impairments in the following three areas: communication, social relationships and restricted patterns of behavior.

The spectrum ranges from those who are severely affected, less able, and dependent on others to those who are of above-average intelligence and independent, yet lacking in social skills.