Seizures are categorized into two main types: focal seizures and generalized seizures.

• Focal seizures (also called focal onset seizures) begin on one side of the brain and may affect awareness, behavior, sensation, or cause abnormal movements usually on one side of the body. They can sometimes spread to both sides of the brain, leading to loss of consciousness and involvement of both sides of the body.
• Generalized seizures (also called generalized onset seizures) begin in both sides of the brain at the same time and usually cause loss of consciousness or awareness, affecting both sides of the body with abnormal movements.

These two types are distinguished primarily by where the seizure starts in the brain and how they affect a person's awareness and movements.