Moving a person or group from a place of residence and prohibiting their residence in certain areas.
Internal exile (e.g. to a gulag or Homeland) is often punishment for conceived crimes against the state and may be a principal or an additional form of punishment. External exile or expulsion is usually used most often against foreigners individually or as organization members, who have entered the country illegally, committed some crime, are a threat to public safety, public morality, or national security. At one time it was used to expel those who are a burden to society, like gypsies, beggars or vagrants. While expulsion of foreigners is a right of a sovereign state, there is no agreement in international law that clearly defines the reasons for expulsion. Voluntary exile is practised by those who for political, economic, social or personal reasons change their nations of residence.
Exile and related forms of ostracism such as internal exile and house detention are humane ways of punishing enemies of the state. In some countries judicial homicide and assassination are the alternative methods.
Expulsion does not cure a problem; it simply removes an instance of it.