Kiribati, independent republic within the Commonwealth of Nations, located in the central Pacific Ocean, about 4,000 km (about 2,500 mi) southwest of Hawaii. It is part of the division of the Pacific islands that is known as Micronesia. Kiribati consists of 33 coral islands divided among three island groups: the Gilbert Islands, the Phoenix Islands, and the Line Islands. All of the islands are atolls (ring-shaped islands with central lagoons) except for the island of Banaba in the Gilbert Islands. Of the 33 islands of Kiribati, 21 are inhabited. Most of the population is concentrated in the Gilbert Islands. Only one of the Phoenix Islands and three of the Line Islands are permanently inhabited. The capital of Kiribati is Tarawa, an atoll in the Gilbert Islands. Bairiki, an islet of Tarawa, serves as an administrative center.