ADHD is a disorder marked by inattention, hyperactivity, and impulsivity. It often arises in early childhood and causes difficulties at home, school, and work. Symptoms include an inability to focus, being easily distracted, excessive talking or movement, and difficulty waiting or following instructions. A diagnosis requires that symptoms be present in multiple environments and negatively impact functioning. While it was traditionally thought children outgrow ADHD, it is now understood the disorder persists into adulthood for many individuals. Effective management includes behavioral and medical interventions.