An open border is a border that enables free movement of people between jurisdictions with no restrictions on movement and is lacking substantive border control. A border may be an open border due to intentional legislation allowing free movement of people across the border, 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. An example of the former is the Schengen Agreement between most members of the European Economic Area. 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.

Immigration is the international movement of people to a destination country of which they are not usual residents or where they do not possess nationality in order to settle as permanent residents. Commuters, tourists, and other short-term stays in a destination country do not fall under the definition of immigration or migration; seasonal labour immigration is sometimes included, however.