Seizures are periods of sustained hyperactivity in the brain. During a seizure, the nerve cells leave their normal actvities, and fire in missive, synchronized bursts. After a few seconds or minutes, the brain regains control and the person returns to normal. There are different types of seizures, however, and different types of epilepsy.
Source: {http://www.sturge-weber.org/medical-matters/seizures-and-neurological-issues.html}