Micronesia is a subregion of Oceania, composed of thousands of small islands in the western Pacific Ocean. It has a shared cultural history with two other island regions, Polynesia to the east and Melanesia to the south.
The region has a tropical marine climate, and is part of the Oceania ecozone. There are four main archipelagos along with numerous outlying islands.
Micronesia is divided politically among several sovereign countries. One of these is the Federated States of Micronesia, which is often called "Micronesia" for short and is not to be confused with the overall region. The Micronesia region encompasses five sovereign, independent nations - the Federated States of Micronesia, Palau, Kiribati, Marshall Islands, and Nauru - as well as three U.S. territories in the northern part: Northern Mariana Islands, Guam, and Wake Island.
Micronesia began to be settled several millennia ago, although there are competing theories about the origin and arrival of the first settlers. The earliest known contact with Europeans occurred in 1521, when Ferdinand Magellan reached the Marianas. The coinage of the term "Micronesia" is usually attributed to Jules Dumont d'Urville's usage in 1832, however Domeny de Rienzi had used the term a year previously.
The Federated States of Micronesia is an independent sovereign island nation and a United States associated state consisting of four states – from west to east, Yap, Chuuk, Pohnpei and Kosrae – that are spread across the Western Pacific Ocean. Together, the states comprise around 607 islands (a combined land area of approximately 702 km² or 271 sq mi) that cover a longitudinal distance of almost 2,700 km (1,678 mi) just north of the equator. They lie northeast of New Guinea, south of Guam and the Marianas, west of Nauru and the Marshall Islands, east of Palau and the Philippines, about 2,900 km (1,802 mi) north of eastern Australia and some 4,000 km (2,485 mi) southwest of the main islands of Hawaii.
While the FSM's total land area is quite small, it occupies more than 2,600,000 km² (1,000,000 sq mi) of the Pacific Ocean, giving the country the 14th largest Exclusive Economic Zone in the world. The capital is Palikir, located on Pohnpei Island, while the largest city is Weno, located in the Chuuk Atoll.
Each of its four states is centered on one or more main high islands, and all but Kosrae include numerous outlying atolls. The Federated States of Micronesia is spread across part of the Caroline Islands in the wider region of Micronesia, which consists of thousands of small islands divided among several countries. The term Micronesia may refer to the Federated States or to the region as a whole.
The FSM was formerly a part of the Trust Territory of the Pacific Islands (TTPI), a United Nations Trust Territory under U.S. administration, but it formed its own constitutional government on May 10, 1979, becoming a sovereign state after independence was attained on November 3, 1986 under a Compact of Free Association with the United States. Other neighboring island entities, and also former members of the TTPI, formulated their own constitutional governments and became the Republic of the Marshall Islands (RMI) and the Republic of Palau (ROP). The FSM has a seat in the United Nations.