Autism is a neurodevelopmental disorder that affects communication, social interaction and behavior. It manifests itself in a variety of ways and is considered a spectrum, meaning that people with this condition may have a wide range of symptoms, abilities and levels of functioning. Signs usually appear during early childhood, and the disorder accompanies the person throughout his or her life. Common features of autism include difficulties in verbal and nonverbal communication, repetitive patterns of behavior, restrictive interests and sensory sensitivity. Individuals often have difficulty understanding social cues, expressing emotions and establishing interpersonal relationships. Although the exact cause remains unknown, it is believed to be the result of a combination of genetic and environmental factors. Diagnosis is made by clinical observation and evaluation of the child's development. Although there is no cure for autism, early interventions, such as behavioral and occupational therapy, can help improve the quality of life for people with autism.