ADHD is a condition where you have lots of energy and have difficulty concentrating. You might also find it hard to control what you say and do. For example, you might speak without thinking first, or find that you do things on impulsively without stopping and thinking about whether this is a good choice or the impact on others it may have.
Symptoms usually start very early in life, before the age of six. We don't know exactly what causes ADHD but experts think it might run in families, or it could be to do with the way the chemicals in your brain work.
There are three types of ADHD:
1. Hyperactive / impulsive type where someone is always on the go as if they were driven by a motor.
2. Inattentive type were someone has difficulty concentrating and focusing their attention.
3. Combined type where someone displays both hyperactive / impulsive and inattentive behaviours.