On September 27, the Free Software Foundation (FSF) celebrates the 40th anniversary of the GNU operating system and the launch of the free software movement. Free software advocates, tinkerers, and hackers all over the world will celebrate this event, which was a turning point in the history of computing. Forty years later, GNU and free software are even more relevant. While software has become deeply ingrained into everyday life, the vast majority of users do not have full control over it.
Basically when you log into your Linux pc, everything you see and click on is GNU. Only the invisible part that makes your hardware work (display driver, usb driver, printer driver etc) is Linux (the kernel)
The kernel recognises only hardware and peripherals. Everything else you do on your system is GNU.