Category
The word category (plural categories; from Greek κατηγορια meaning "assertion" or "accusation", hence 'categorical denial') has several meanings:
- it is used informally to mean a class of things, as in "the category of all living things"
- in philosophy:
- notably, Aristotle classified all things into 10 categories
- others have made similar classifications, see categories of being
- Kant uses the word for the preconceived notions we use to organize sense data
- in mathematics:
- a collection of mathematical objects of the same kind, together with the structure-preserving maps between them; as in "the category of all topological spaces and continuous maps". These are studied in category theory.
- in topology, one distinguishes between sets of first and second category; see Baire space.
- The game, Categories
- on Wikipedia: see Wikipedia:Categorization for more about WP categories.