Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder. It affects how people think and act. People with ADHD may have trouble sitting still, being quiet, or sleeping. They may be rather impulsive. They usually have problems focusing and remembering what is said or done around them, causing problems in school, work, and relationships if not properly managed. However, they can focus extremely well on interesting or urgent tasks, often longer and more intensely than those without the condition. This is called hyperfocus, and is a potential benefit and drawback depending on the context. ADHD is called a neurological developmental disorder because it affects how people's nervous systems develop.