Learn More:
What Is Autism? What is Autism Spectrum Disorder?
http://www.autismspeaks.org/what-autism
"Autism spectrum disorder (ASD) and autism are both general terms for a group of complex disorders of brain development."

What Is Autism Spectrum Disorder?
http://www.nimh.nih.gov/health/topics/autism-spectrum-disorders-asd/index.shtml
"The term "spectrum" refers to the wide range of symptoms, skills, and levels of impairment or disability that children with ASD can have."

Facts About ASD
http://www.cdc.gov/ncbddd/autism/facts.html
"Autism spectrum disorder (ASD) is a developmental disability that can cause significant social, communication and behavioral challenges."

Autism Spectrum Disorder
http://www.dsm5.org/Documents/Autism%20Spectrum%20Disorder%20Fact%20Sheet.pdf
"One of the most important changes in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) is to autism spectrum disorder (ASD)."