|This is a container category. Due to its scope, it should contain only subcategories.|
- A priori constructed worlds refer to constructed worlds which are based in originally based universes. These include fantasy, soft science fiction, and magic-based worlds. Any constructed worlds deliberately set outside of Earth and/or outside "our universe" may fall under this category.
- A posteriori constructed worlds refer to constructed worlds which are based in our reality or the real world. These include alternate history timelines (including ASB timelines), hard science fiction, and future history scenarios. It also includes constructed worlds based on existing franchises or intellectual property, such as fandom-based universes or fan fictional universes. Any constructed worlds deliberately set on Earth or in "our universe" may fall under this category.
Note: Some constructed worlds may fall in both categories or subcategories from both sides. Examples include ASB alternate history which are based on Earth but may have fantastical elements or horror-based constructed worlds, which may be set in the real world or their own world.