Northern Ireland is the smallest of the four components of the United Kingdom in terms of both area and population, containing 2.9% of the total population and 5.7% of the total area of the United Kingdom. It is the smaller of the two political entities on the island of Ireland by area and population, the other being the Republic of Ireland. Northern Ireland contains 27.1% of the total population and 16.75% of the total area of the island of Ireland.