Please refer to the releases web page for information on how to obtain GCC.
The full distribution includes the C, C++, Objective-C, Fortran, Java, and Ada (in the case of GCC 3.1 and later) compilers. The full distribution also includes runtime libraries for C++, Objective-C, Fortran, and Java. In GCC 3.0 and later versions, the GNU compiler testsuites are also included in the full distribution.
If you choose to download specific components, you must download the core GCC distribution plus any language specific distributions you wish to use. The core distribution includes the C language front end as well as the shared components. Each language has a tarball which includes the language front end as well as the language runtime (when appropriate).
Unpack the core distribution as well as any language specific distributions in the same directory.
If you also intend to build binutils (either to upgrade an existing installation or for use in place of the corresponding tools of your OS), unpack the binutils distribution either in the same directory or a separate one. In the latter case, add symbolic links to any components of the binutils you intend to build alongside the compiler (bfd, binutils, gas, gprof, ld, opcodes, ...) to the directory containing the GCC sources.
Likewise the GMP, MPFR and MPC libraries can be automatically built together with GCC. Unpack the GMP, MPFR and/or MPC source distributions in the directory containing the GCC sources and rename their directories to gmp, mpfr and mpc, respectively (or use symbolic links with the same name).