An open border is a border that enables free movement of people and often of goods between jurisdictions with no restrictions on movement and is lacking a border control. A border may be an open border due to intentional legislation allowing free movement of people across the border (de jure), or a border may be an open border due to a lack of legal controls, a lack of adequate enforcement or adequate supervision of the border (de facto). An example of the former is the Schengen Agreement between most members of the European Economic Area (EFTA and the EU). An example of the latter has been the border between Bangladesh and India, which is becoming controlled. The term "open borders" applies only to the flow of people, not the flow of goods and services, and only to borders between political jurisdictions, not to mere boundaries of privately owned property.
Open borders are the norm for borders between subdivisions within the boundaries of sovereign states, though some countries do maintain internal border controls (for example between the People's Republic of China mainland and the special administrative regions of Hong Kong and Macau, between the United States and the unincorporated territories of Guam, the Northern Mariana Islands and American Samoa, and the Minor Outlying Islands, or between North Korea's provinces and cities). Open borders are also usual between member states of federations, though (very rarely) movement between member states may be controlled in exceptional circumstances. Federations, confederations and similar multi-national unions typically maintain external border controls through a collective border control system, though they sometimes have open borders with other non-member states through special international agreements – such as between Schengen Agreement countries as mentioned above.
