Autism spectrum disorder (ASD) is a neurological and developmental condition that begins early in childhood and lasts throughout a person's life. It affects how a person acts, interacts with others, communicates, and learns. ASD is a spectrum disorder, meaning individuals can have a range of symptoms, including difficulties in social interactions, communication problems, and repetitive behaviors. The causes of ASD are not fully understood, but research suggests that both genes and the environment play important roles. Early intervention services can greatly improve the development of a child with ASD. Treatments for ASD include behavior and communication therapies, skills training, and medications to control symptoms. People with ASD may have a wide range of intellectual abilities and language skills, with some individuals having advanced conversation skills while others may be nonverbal. Symptoms of ASD can manifest as early as 1 to 2 years of age, with impaired social skills, communication problems, and repetitive actions being key characteristics. Individuals with ASD may have difficulties developing and maintaining friendships, communicating with peers and adults, and understanding expected behaviors in various settings. The disorder can cause impairment in personal, family, social, educational, occupational, or other important areas of functioning.