Newbies often get confused with the concept of GNU and Linux. Most people end up saying GNU/Linux as ‘Linux’. The important thing here to understand is most people don’t directly use Linux. This may sound contradict but Linux is just a core part of an operating system. It’s task is to handle underlying hardware.
Users work on application, and applications can’t talk directly to hardware, they take help of Linux-kernel. Major Free and Open source applications(Libre Office, VLC media player etc.) are licensed under GNU License. In fact the basic core-utils packages used in Linux like copy, move etc. are GNU applications.