[Haskell-cafe] what exactly does "deriving (Functor, Monad, MonadIO)" do?

[Thomas Hartman]

I was trying to follow the reasoning in Don's article on using haskell
for shell scripting

  http://cgi.cse.unsw.edu.au/~dons/blog/2007/03/10

In the source listing at the end we is

      newtype Shell a = Shell { runShell :: ErrorT String IO a }
        deriving (Functor, Monad, MonadIO)

and I don't understand it what "deriving" is doing here, nor have I
been able to find documentation on it.

  http://en.wikibooks.org/wiki/Haskell/Class_declarations

claims:

"You can only use deriving with a limited set of built-in classes. They are:

Eq  Ord Enum Bounded  Show  Read "

But, here we are deriving classes not in that list. So, is this a
recently added feature? Or something that came in from

  {-# OPTIONS -fglasgow-exts #-} ?

I would just like to understand this, and I can't figure out how to begin.

Thanks for any help!

thomas.