Autism spectrum disorder (ASD) is a developmental disorder. It affects a person's behaviour and makes communication and social interactions difficult. People who have ASD are born with it.

In most cases, symptoms of ASD are noticed by the time a child is 2 years old. But if symptoms are severe, a parent may notice them as early as when a child is 12 months old.

The type of symptoms a person has and how severe they are varies.

Treatment includes behavioural training, speech and occupational therapy, and parent education and support.

ASD now includes conditions that used to be diagnosed separately. These include autism, Asperger's syndrome, pervasive developmental disorder, and childhood disintegrative disorder.