What I think a Monad is

gistfile1.txt

A monad is a datatype used to describe actions. Wait, what? What do you mean
'describe an action'?!

Well, at least in Haskell, we're not really using actions or statements; we're
using mathematical transformations. But sometimes, we really want to think of
something a 'doing' something to another thing. In those circumstances, due to
Haskell's semantics, we need a sort of mathematical description of what 'doing
something to something else' means.

The mathematical abstraction of this is a monad.

[I am not a category theorist, so this is probably completely wrong, but this
definition works for me.]