Oceania (sometimes Oceanica ) is a geographical, often geopolitical, region consisting of numerous lands—mostly islands in the Pacific Ocean and vicinity. The term "Oceania" was coined in 1831 by French explorer Dumont d'Urville. The term is used today in many languages to define one of the continents and is one of eight terrestrial ecozones. The term is sometimes applied to the Australian continent.

Ethnologically, the islands that are included in Oceania are divided into the subregions of Melanesia, Micronesia, and Polynesia.  Minor parts of Melanesia, and all of Micronesia and Polynesia do not make up the continental land mass of Oceania.

The boundaries of Oceania are defined in a number of ways. Most definitions recognize parts of Australasia such as Australia, New Zealand, and New Guinea, and all or part of the Malay Archipelago are included in Oceania.