Wikipedia Organization

Wikipedia has the following views:
Categories | Outlines | Portals | Overviews | Lists | Glossaries

There are all views for each subject area and all subject areas for each view.
Subject areas are collections of articles.

There are also indexes (A-Z index, 3rd party indices, etc.)

Content Style
https://en.wikipedia.org/wiki/Wikipedia:Categorization
https://en.wikipedia.org/wiki/Wikipedia:FAQ/Categorization
https://en.wikipedia.org/wiki/Wikipedia:Categories,_lists,_and_navigation_templates
https://en.wikipedia.org/wiki/Wikipedia:What_Wikipedia_is_not
https://en.wikipedia.org/wiki/Wikipedia:Writing_better_articles