Border controls are measures used by a country to monitor or regulate its borders.
The control of the flow of many people, animals and goods across a border may be controlled by government Customs services. Security is enforced by various kinds of Border Guards and Coast Guards. Official designations, jurisdictions and subordinations of these agencies vary.
Border controls exist to:
The degree of strictness of border controls depends on the country and the border concerned. In some countries, control may be targeted at the traveller's national origin or other countries that have been visited. Others may need to be certain the traveller has paid the appropriate fees for their visas and has future travel planned out of the country. Yet others may concentrate on the contents of the travellers baggage, and imported goods to ensure nothing is being carried that might bring a biosecurity risk into the country. In the member states of the Schengen agreement, internal border control is often virtually unnoticeable, and often only performed by means of random car or train searches in the hinterland, while controls at borders with non-agreement states may be rather strict.
Sometimes border controls exist on internal borders within a country. For example, in the People's Republic of China, there are border controls at the borders among the mainland and the Special Administrative Regions of Hong Kong and Macau, even though they are part of the same country.