What is a GCC toolchain?

In which ways it can be an example of C/assembly/object/executable compiler?

I would like more pieces of information than the few ones Wikipedia gives about it. Also, if you can link some sources where I could find more about it, it would be great.

Solution

From Wiktionary, a toolchain is:

A set of tools for software development, often used in sequence so that the output of one tool comprises the input of the next.

GCC is the GNU Compiler Collection; i.e. a set of compilers for different languages from GNU. From the official webpage:

The GNU Compiler Collection includes front ends for C, C++, Objective-C, Fortran, Ada, and Go, as well as libraries for these languages (libstdc++,...).

Therefore, the GCC toolchain is a set of applications and libraries to compile programs written in several languages. For instance, for the C and C++ languages, that includes tools like:

cpp Preprocessor
gcc C compiler
g++ C++ compiler
gcov Test coverage program

And accompanying libraries like:

libbacktrace Symbolic backtraces producer
libquadmath Quad-Precision Math Library
libstdc++-v3 C++ Standard Library

Now, when someone refers to the GCC toolchain, typically they are also implicitly referring to other utilities that might not come from GCC's project/repository but are usually required for development. For instance, tools like:

ar Archive manipulation program
as Assembler
c++filt C++ demangler
ld Linker
nm Object file symbol listing
objdump Object file information dumper

If you are using the implementation of these tools from GNU, then you are using the GNU Binutils project:

The GNU Binutils are a collection of binary tools.