The GNU toolchain is a term used for a collection of programming tools under the GNU Project umbrella. This suite of tools is what is normally called a toolchain, and is used for the development of applications and operating systems. It plays an important role in the development of embedded systems and Linux systems, in particular.
The following projects are included in the GNU toolchain:
GNU make: This represents an automation tool used for compilation and build
GNU Compiler Collection (GCC): This represents a compiler's suite that is used for a number of available programming languages
GNU Binutils: This contains tools, such as linkers, assemblers, and so on - these tools are able to manipulate binaries
GNU build system (autotools): This consists of the following:
Autoconf
Autoheaders
Automake
Libtool