Immigration detention is the policy and practice of incarcerating both foreign national asylum seekers/refugees and immigrants — whether suspected of unauthorized arrival, illegal entry, visa violations, as well as those subject to deportation and removal — in detention centers for the purpose of immigration control, until a decision is made by immigration authorities to grant a visa and release them into the community, or to repatriate them to their country of departure. Mandatory detention refers to the practice of compulsorily detaining or imprisoning people who are considered to be illegal immigrants or unauthorized arrivals into a country. Some countries have set a maximum period of detention, while others permit indefinite detention.