Scientifically known as AD/HD (Attention Deficit/Hyperactivity Disorder), there are three types:
1)The predominantly hyperactive-impulsive type
2)The predominantly inattentive type
3)The combined type
The term ADD is a term that has circulated the media which has the same meaning, but generally applies only to the predominatly inattentive type.
The proven causes of AD/HD are low glucose levels in the brain and genetic factors (inheritance via a family member).
The most effective treatments of AD/HD are medications such as Adderall and Ritalin. Diet changes may also help, but cannot be guaranteed (changing diet to fish oils and fatty acids).
Finally, AD/HD is a legitamate disorder and to say otherwise is complete and utter bullshit, not to mention an opinion supported by backward old farts who still spank their children.
If you are consistently restless and/or have trouble paying attention in class on a regular basis, chances are you have AD/HD!