1. In its narrow usage it refers to:

• Polynesia (including New Zealand and the Hawaiian Islands),
• Melanesia (including New Guinea and the Solomon Islands),
• Micronesia

Wikimedia Commons has media related to Oceania.

Oceania is a name used for varying groups of islands of the Pacific Ocean.

2. In a wider usage it includes: Australia.
3. It may also include: the Malay archipelago.
4. In uncommon usage includes islands such as: Japan and the Aleutian Islands.

• Continent: The islands of Oceania and the continent of Australia form a geographic region which is sometimes, for the purposes of dividing the whole world into areas, called a 'continent'. As such, it is the smallest "continent" in area and the second smallest, after Antarctica, in population.