[heinrichhartman]

Categories are Algebraic structures, that are related to this hierarchy:

- Monoids are Categories with a single object.

- Algebras (Non-commutative, Associative) are k-linear Categories, with a single object.

- Any object X in a k-linear category comes with an algebra: R = End(X) = Hom(X,X).

- Any other objects comes with an R-module: Hom(R, X)

- In some cases, we can use this to describe the category as a category of R modules: https://en.wikipedia.org/wiki/Gabriel%E2%80%93Popescu_theore...