You may have seen an autistic child or adult and never knew that the person had a diagnosis. Your ignorance about the disorder is not uncommon because most people who are not experienced with the disorder look at autistic people as those who are mentally retarded or have some learning disability. This is not true.
Autism is a very complicated disorder that affects children typically from the age of three to conception. The disorder is neurological in nature and primarily affects the areas of the brain where communication and social interaction is developed.