Together with Bonaire and Curaçao, Aruba forms a group referred to as the ABC islands. Collectively, Aruba and the other Dutch islands in the Caribbean are often called the Netherlands Antilles or the Dutch Caribbean. Aruba is one of the four constituent countries that form the Kingdom of the Netherlands, along with the Netherlands, Curaçao and Sint Maarten. The citizens of these countries all share a single nationality: Dutch. Aruba has no administrative subdivisions, but, for census purposes, is divided into eight regions. Its capital is Oranjestad.