Epilepsy is not a single disease but rather a large group of disorders whose common feature is the tendency to have recurrent epileptic seizures. Epileptic seizures are events which are caused by abnormal electrical discharges in the brain. They can take many different forms, ranging from brief, blank stares to convulsions (characterised by body stiffening and repetitive limb jerking).
Because, epilepsy is the tendency to have recurrent epileptic seizures, it is usually not formally diagnosed until at least two have occurred. Many different underlying problems can give rise to epilepsy. It can be a consequence of another underlying problem, such as cerebral palsy, a brain tumour or a head injury. This is sometimes called symptomatic epilepsy.