What Is Autism Spectrum Disorder?
Autism spectrum disorder (ASD) is a developmental disability that is caused by differences in how the brain functions. People with ASD may communicate, interact, behave, and learn in different ways. Signs of ASD begin during early childhood and usually last throughout a person’s life.
Previously, the term “ASD” collectively referred to the following three conditions that were diagnosed separately: autistic disorder, pervasive developmental disorder not otherwise specified (PDD-NOS), and Asperger disorder. ASD now encompasses a single diagnosis of “autism spectrum disorder”. The term “spectrum” in ASD means that each person can be affected in different ways, and symptoms can range from mild to severe. People with ASD share some similar symptoms, such as difficulties with social interaction, difficulties with communication, and highly focused interests and/or repetitive activities. How the symptoms affect a person’s functioning depends on the severity and combination of those symptoms.
Taken from the CDC website