Find out more about the GNU Project.
GNU Are working on a GNU OperatingSystem, using TheHurd as the Kernel and using GNU UserSpace utilities
RMS wants you to refer to a Linux distribution as GNU/Linux.
His logic is that "Linux" is a Kernel, and it uses mostly GNU UserSpace utilities. Thus the OperatingSystem as a whole is "GNU/Linux". The sense in that is that glibc was made by the GNU project, as was sysvinit and a number of other crucial system components.
If the majority of UserSpace is under a GNU License? or BSD License? or other Licences?, doesn't appear to enter into this dicussion for some reason.
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