Epilepsy is a seizure disorder. According to the Epilepsy Foundation of America, a seizure happens when a brief, strong surge of electrical activity affects part or all of the brain.  Seizures can last from a few seconds to a few minutes. They can have different symptoms, too, from convulsions and loss of consciousness, to signs such as blank staring, lip smacking, or jerking movements of arms and legs. 
Some people can have a seizure and yet not have epilepsy. For example, many young children have convulsions from fevers. Other types of seizures not classified as epilepsy include those caused by an imbalance of body fluids or chemicals or by alcohol or drug withdrawal. Thus, a single seizure does not mean that the person has epilepsy. Generally speaking, the diagnosis of epilepsy is made when a person has two or more unprovoked seizures. 
This information is from the National Dissemination Center for Children with Disabilities (NICHCY).
It’s very helpful to read more about epilepsy. Following are links to additional information:
NICHCY Epilepsy Resources
The National Dissemination Center for Children with Disabilities (NICHCY) offers brief, but detailed fact sheets on Epilepsy. Each fact sheet defines the disability, describes its characteristics, offers tips for parents and teachers, and connects you with related information and organizations with special expertise.
Epilepsy Association of Utah
The Epilepsy Association of Utah is dedicated to providing education and support services for individuals and families dealing with the many challenges of Epilepsy.
Epilepsy.com is an online resource provided by The Epilepsy Project. Their mission is to inform and empower two groups of patients and their families: those facing newly diagnosed epilepsy, and those struggling with epilepsy that has resisted treatment.