Epilepsy is a condition in which a person has recurrent seizures. A seizure is defined as an abnormal, disorderly discharging of the brain's nerve cells, resulting in a temporary disturbance of motor, sensory, or mental function.
There are many types of seizures, depending primarily on what part of the brain is involved. The term epilepsy says nothing about the type of seizure or cause of the seizure, only that the seizures happen again and again. A stricter definition of the term requires that the seizures have no known underlying cause. This may also be called primary or idiopathic epilepsy.