Micronesia is a subregion of Oceania made up of around 2,000 tiny islands in the western Pacific Ocean. It shares a tight cultural history with three other island groups: the Philippines to the west, Polynesia to the east, and Melanesia to the south—as well as the larger Austronesian community.
The area is part of the Oceanian domain and has a tropical marine climate. It consists of four major archipelagos: the Caroline Islands, the Gilbert Islands, the Mariana Islands, and the Marshall Islands, as well as countless islands that are not part of any of the archipelagos.
Political control of places within Micronesia varies per island and is shared by six sovereign countries. Some Caroline Islands are part of the Republic of Palau, while others are part of the Federated States of Micronesia (commonly abbreviated as "FSM" or "Micronesia"—not to be mistaken with the similar name for the whole area). The Republic of Kiribati is made up of the Gilbert Islands, the Phoenix Islands, and the Line Islands in Polynesia. The Mariana Islands are associated with the United States, and some of them are owned by the United States. The territory of Guam and the remainder are owned by the United States. Northern Mariana Islands Commonwealth Nauru is a sovereign country in its own right. The Republic of the Marshall Islands owns all of the Marshall Islands. Wake Island's sovereignty is disputed; it is claimed by both the United States and the Republic of the Marshall Islands. The US holds real control of Wake Island, which is under the direct administration of the US Air Force.
Micronesia's human habitation started millennia ago. According to linguistic, archaeological, and human genetic evidence, the Micronesian people are a subset of the sea-migrating Austronesian people, which also includes the Polynesian and Melanesian people. According to current scholarly opinion, the Austronesian peoples descended from a prehistoric seaborne migration known as the Austronesian expansion, which occurred between 3000 and 1500 BCE from pre-Han Taiwan. Around 2200 BCE, Austronesians arrived in the northernmost Philippines, notably the Batanes Islands. Austronesians were the first to create ocean-going sailing technology (particularly catamarans, outrigger boats, lashed-lug boat construction, and the crab claw sail), allowing them to disperse quickly across the Indo-Pacific islands. They absorbed (or were assimilated by) the older people on the islands along their migratory route beginning about 2000 BCE.
The first documented European encounter with Micronesia occurred in 1521, when Spanish ships arrived in the Marianas. The name "Micronesia" is commonly attributed to Jules Dumont d'Urville in 1832, while Domeny de Rienzi used it a year earlier.