A border is an edge or boundary, most frequently of a country. The longest border between two countries is the United States-Canada border. They can be very complex with enclaves and exclaves, such as the India-Bangladesh border. Border disputes can simmer for decades, e.g. the Kashmir region divided between Pakistan and India.
The Armenia-Turkey border is an example of a closed border. 65 countries have built a wall on (some of) their borders. The best-known walls are on the Israel-Palestine border, and on the United States-Mexico border (partially built at the moment). Among the benefits of border security, lands along the border are safe and the quality of parks along the border is increased.
Another phenomenon is open borders, where a number of countries agree to give full access to civilians and goods of other member states to enter their territory, e.g. the European Union. Donald Trump famously remarked that "A nation without borders isn't a nation".
- Dinan, Stephen (October 1, 2017). Successful border enforcement saves habitat, visitor security on National Park Service land. The Washington Times. Retrieved October 2, 2017.