What is seizure exactly ?

There are many types: En.Wikipedia.Org/wiki/seizure_types please reference the above article for an excellent discussion of the various types of seizures. Seizures can have many different causes. A seizure is basically an abnormal electrical discharge in the brain caused by a part of the brain being irritated. The electrical discharge can be localizedaffecting just one part of many of the brains functions or it can generalize and spread across the brain causing a grand mal seizure which is where the person actually loses consciousness and has jerking activity throughout their entire body. Pleasant reading and best wishes.

Abnormal electricity: An epileptic seizure is an abnormal electrical discharge of the brain. It usually causes abnormal behavioral change; less commonly there may be no overt behavioral change, though the person may have a lapse of time.