Attention deficit hyperactivity disorder is a group of behavioural symptoms that include inattentiveness, hyperactivity and impulsiveness. In fact, it is a medical condition that affects how well can someone sit still, focus and pay attention. Generally, ADHD affected children have differences in the parts of their brains that control activity and attention. It means that such individuals may have some problems focussing in some activities. They may be hyperactive or may be unable to control their impulses.