[twincling] new variable types in C

[eerpinisatish]

hi all, 
i have a small doubt, how are variable type like int , or float
actually defined in C, like if i want to define a new variable type ,
which is say completely new, then how do i do it and then use it again
and again in my programs ??, is it something like the library
functions , or is there a different method ??