This character is a Other Symbol and is commonly used, that is, in no specific script. The character is also known as island.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. U+1F3DD offers a line break opportunity at its position, except in some numeric contexts.
The CLDR project calls this character “desert island” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: desert, island.
This character is designated as an emoji. It will be rendered as monochrome character on conforming platforms. To enable colorful emoji display, you can combine it with Variation Selector-16: 🏝️ See the Emojipedia for more details on this character’s emoji properties.
The Wikipedia has the following information about this codepoint:
An uninhabited island, desert island, or deserted island, is an island, islet or atoll that is not permanently populated by humans. Uninhabited islands are often depicted in films or stories about shipwrecked people, and are also used as stereotypes for the idea of "paradise". Some uninhabited islands are protected as nature reserves, and some are privately owned. Devon Island in Canada's far north is the largest uninhabited island in the world.
Small coral atolls or islands usually have no source of fresh water, but occasionally a freshwater lens can be reached with a well.