(CNN) -- Here are some fast facts about autism.
April 2 is World Autism Day.
From the Centers for Disease Control and Prevention: Autism or autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders, causing impaired communication skills and social skills. ASDs generally start before three years of age and last a lifetime, but early intervention plays a role in treatment and progress.
Types: From the American Psychiatric Association, Diagnostic and Statistical Manual (DSM V) There are several types of ASDs: Autistic Disorder, Asperger Disorder, Childhood Disintegrative Disorder, and Pervasive Developmental Disorder.
Possible characteristics: According to the American Academy of Pediatrics, "The main characteristics of autism are difficulties in social interaction, communication, and restrictive and repetitive interests and activities."
The National Autism Association on the "Signs of Autism."
Boys are five times more likely than girls to have ASDs.
ASDs can be found amongst all races, ethnicities, and socioeconomic groups.
Estimates: The CDC on "Determining How Many People Have ASDs."
World: Tens of millions worldwide are affected with ASD (Autism Speaks)
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Fast facts: What is autism?