Online ADHD Test Free: Understanding Attention-Deficit/Hyperactivity Disorder Through Self-AssessmentAttention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder that often starts in childhood and can continue into adulthood. It is identified by symptoms such as inattention, hyperactivity, and impulsivity, which can result in substantial challenges in individual, scholastic, and expert settings.