ADHD is a common behavioural disorder that affects about 5% of school-age children. It can also affect people of all ages, and is considered a neuro-behaviourial developmental disorder by psychiatrists.
An individual with ADHD finds it a lot harder to focus on something without being distracted. He has greater difficuly in controlling what he is doing or saying and is less able to control how much physical activity is appropriate for a particular situation, compared to somebody without ADHD.
Of course, all kids (especially younger ones) act this way at times, particularly when they’re anxious or excited. But the difference with ADHD is that symptoms are present over a longer period of time and occur in different settings. They impair a child’s ability to function socially, academically, and at home.