[Q] How to make a mode dependent operation ?

[Fren Zeee]

Here is a simple newbie problem :

In c-mode, I want to insert a skeleton of function as

 () {


}

and In lisp-mode, I want

( defun ()
""

)

and similarly in scheme, java, python, haskell, pascal ...

What is the quick but maybe not the dirty way to do it ?

What is the PRO way to do it ? I have heard a little about the hooker
hooks :)

What is a hook and what is proper place of use ? Is it appropriate for
this kind of private customization ?