Is gcc a complete universal (not bound to any OS) c compiler?

[Shawn Cyberpunk]

When i asked someone about the best c compiler to use, he advised me to 
look at gcc.
The problem is that i am a windows user and novice programmer and he is 
a die-hard linux fan.
So he can't answer me when i ask him if gcc is unix implemented: e.g. if 
there are some unix components in it incompatible with windows and as a 
result need some kind of nix emulation OR if gcc is a fully 
os-independant universal C compiler(and if yes, how do i get unemulated 
win binaries?).
So could you answer this question?