I found this interesting page at Wiki Haskell. Confusing, however, is how it first establishes

data Peano = Zero | Succ Peano

It says

Here Zero and Succ are values (constructors). Zero has type Peano,

and Succ has type Peano -> Peano.

but then it breaks down each member further a few lines later

data Zero
data Succ a

and then says

Zero has kind *, and Succ has kind * -> *. The natural numbers are represented by types (of kind *) Zero, Succ Zero, Succ (Succ Zero) etc.

Why is it giving two separate treatments and what is meant by the * and * -> * ? There's something fundamental I'm missing.

If anyone knows of a really thorough and definitive and understandable treatment of Haskell types, I'd appreciate it.