Autism Spectrum Disorder (ASD) is a neurodevelopmental condition that affects communication, behavior, and social interaction. Once classified under five subtypes, ASD now includes four major types: Autism, Asperger Syndrome, Childhood Disintegrative Disorder, and Pervasive Developmental Disorder - Not Otherwise Specified (PDD-NOS). Each type has unique traits, making accurate diagnosis essential for effective treatment. The classification also includes defined severity levels to help guide therapy and support plans. Learn how modern diagnosis and classification systems improve outcomes for individuals with ASD.