Compiler: Compiler is a computer program which transforms source code written in one programming language into another language (generally binary code,machine code ).
C compiler: C compiler converts C program into a binary program. (e.q. C compiler on windows compiles a C program and creates executable .exe file. )
Compilers for various platform / OS :
GCC ( Gnu C compiler ) : A open source C compiler for linux and other operating systems. GCC comes with preinstalled in ubuntu and other linux distribution. For windows we can install cygwin and Ming.