Attention Deficit Hyperactivity Disorder (ADHD) is a condition characterized by symptoms of inattention, hyperactivity, and impulsivity, typically evident before age seven. Diagnosis should be performed by a qualified professional, as symptoms may be similar to other disorders, and ADHD often co-occurs with conditions like learning disabilities and conduct disorder. While the exact cause of ADHD is unknown, genetic and neurobiological factors are suspected, and stimulant medications are generally effective in treating its symptoms.