API:Allcategories

Get a list of all categories. This differs from list=allpages&alnamespace=14 in that categories without descriptions will be listed, while redirects and pages where the category was never used will not. Note: the  list includes categories that were previously used but have since been deleted. It is recommended that the list be filtered to those where the size is greater than zero or the category page exists.

Error Codes
None