There are three types of ADHD: 1. ADHD Impulsive/Hyperactive: People with ADHD are impulsive and the hyperactive type is actually the least common of the three. This type is categorized as impulsive behaviors without inattention. 2. ADHD Inattentive/Distractible: This type of ADHD is the second most common type and can be recognized by inattention, forgetfulness, and distractibility without hyperactivity. 3. ADHD Combined: People with ADHD combined type have characteristics of impulsivity/hyperactivity and inattentive/distractible types. This is the most common type of ADHD.