It is used to build and maintain lists of pages—primarily for the sake of the lists themselves. They are not part of the encyclopedia's categorization scheme.
These categories are used to track, build and organize lists of pages needing "attention en masse" (for example, pages using deprecated syntax), or that may need to be edited at someone's earliest convenience.
These categories also serve to aggregate members of several lists or sub-categories into a larger, more efficient list (discriminated by classifications).
Administrators: Please do not delete this category even if it is empty! This category may be empty occasionally or even most of the time.
This category is populated automatically by the MediaWiki software. It contains pages where MediaWiki has detected that the expansion depth limit of 40 levels has been exceeded. If the limit is exceeded then parts of the page can fail to render or be rendered incorrectly. A solution may require to omit or edit a template used on the page. See more at meta:Help:Expansion depth and en:Wikipedia:Avoiding MediaWiki expansion depth limit.