A seizure (epileptic seizure) is a transient clinical manifestation caused by abnormal excessive and synchronized firing activity of brain neurons. Seizures should have three elements: 1. Clinical manifestations: Seizures must have clinical manifestations (symptoms and/or signs). The clinical manifestations of seizures can be varied, such as sensory, motor, vegetative, consciousness, emotional, memory, cognitive and behavioral disturbances. Seizures generally have the common features of sudden onset and termination, transient and self-limiting. The onset and termination of seizures can usually be determined by behavioral manifestations or EEG changes. Persistent status epilepticus is a special condition with persistent or recurrent seizures. 3. Abnormal hyper-synchronized brain discharges: This can only be confirmed by EEG examination. This is the most essential feature that distinguishes seizures from other seizure symptoms. According to the presence or absence of acute triggers, seizures can be broadly classified into provoked seizures (provoked seizure) and non-provoked seizures (unprovoked seizure). Provoked seizures are most commonly seen in the acute phase of central nervous system disease (infection/stroke, etc.) or systemic systemic disease (blood glucose abnormalities/electrolyte disturbances/poisoning/fever, etc.) and are an acute symptomatic seizure. This seizure represents only a symptom of the acute phase of the disease and does not imply that seizures must recur after the acute phase. Non-triggered seizures do not have a clear acute trigger. For example, seizures that occur during the acute phase of viral encephalitis are induced seizures, whereas seizures that occur several years after encephalitis are non-induced seizures. Epilepsy is a brain disorder characterized by a persistent tendency to cause epilepsy. Epilepsy is not a single disease entity, but a chronic brain disease state with different etiological bases and different clinical manifestations, but with recurrent seizures as a common feature. Traditionally, epilepsy is diagnosed when there are two clinical episodes (at least 24 hours apart) of unprovoked seizures. This is the commonly used and clinically operable diagnostic method. In 2005, the International League Against Epilepsy (ILAE) revised the definition of epilepsy and stated that “a single seizure may be required for the diagnosis of epilepsy provided that there is a persistent epileptogenic tendency in the brain”. This definition is positive for the early diagnosis and treatment of epilepsy, but it lacks clinical applicability due to the difficulty of determining the risk of recurrence after an individual’s first seizure in most cases. In 2014, ILAE introduced a new clinically useful definition of epilepsy, and the various potential implications of the new definition are not yet known and will need to be further tested clinically. Third, epileptic syndrome refers to an epileptic disorder consisting of a specific set of clinical manifestations and EEG changes (i.e., an electroencephalographic clinical syndrome). The diagnosis of epileptic syndrome is often made by combining age of onset, seizure type, etiology, anatomical basis, seizure duration, triggering factors, seizure severity, other concomitant symptoms, EEG and imaging findings, past history, family history, response to drugs and regression. The diagnosis of epilepsy syndrome has certain guiding significance for treatment selection and prognosis. Epileptic encephalopathy refers to progressive neuropsychiatric dysfunction or degeneration caused by frequent seizures and/or epileptiform discharges, such as cognitive, language, sensory, motor and behavioral aspects. The impairment may be generalized or selective and may exhibit varying degrees of severity. It is an umbrella term for a group of epileptic disorders. Outside of brain injury due to underlying etiology, epileptic encephalopathy emphasizes progressive encephalopathy due to epileptic abnormalities themselves. West syndrome, Lennox-Gastaut syndrome, and Dravet syndrome are all epileptic encephalopathies.