The Kingdom of the Netherlands is a sovereign state and constitutional monarchy with territory in Western Europe and in the Caribbean. The four parts of the Kingdom — Aruba, Curaçao, the Netherlands, and Sint Maarten — are referred to as countries, and participate on a basis of equality as partners in the Kingdom.
In practice, however, most of the Kingdom affairs are administered by the Netherlands (which comprises roughly 98% of the Kingdom's land area and population) on behalf of the entire Kingdom, with Aruba, Curaçao and Sint Maarten being dependant on the Netherlands.
The country of the Netherlands is located in Europe, except for its three special municipalities that are located in the Caribbean. Aruba, Curaçao and Sint Maarten are located in the Caribbean as well.
The Kingdom of the Netherlands currently consists of four constituent countries that form part of the Kingdom of the Netherlands on a basis of equality. Note that there is a difference between the "Kingdom of the Netherlands" and the "Netherlands": the Kingdom of the Netherlands is the comprehensive sovereign state and the Netherlands is only one of its four countries. Three of the six Dutch Caribbean islands (Aruba, Curaçao, Sint Maarten) each form one of the three remaining constituent countries, while the others (Bonaire, Sint Eustatius, Saba) are actually part of the country of the Netherlands and are collectively known as the Caribbean Netherlands.