- A monad from a category theoretic perspective is a monoid in the category of endofunctors. From a computational perspective, it is defined by return, bind, and monad laws. - Kleisli triples and monads are equivalent based on work by Manes in 1976. Monads can be derived from algebraic operations and equations if they have finite rank based on work by Kelly and Power in 1993. - Algebraic effects classify effects based on algebraic theories and provide a way to modularly combine effects through sums and products. This provides benefits for equational reasoning about monadic programs.