According to the Diagnostic and Statistical Manual (DSM-5), autism spectrum disorder (ASD) is classified as a developmental disorder, with or without intellectual disability (ID), which is characterized by impairment(s) in reciprocal social communication and social interaction (i.e. turn taking activities, such as a two person conversation) and restricted, repetitive patterns of behavior, interests or activities (i.e. an individual who talks exclusively about trains). These characteristics are typically present from early childhood and may limit or impair everyday functioning. The term "spectrum" is used because there are many diagnoses that fall "on the autism spectrum" which used to be treated as separate diagnoses including autistic disorder, pervasive developmental disorder not otherwise specified (PDD-NOS), and Asperger's syndrome. All of these conditions are now considered to be within the autism spectrum and are called ASDs.