From LXF Wiki
Many people insist on referring to Linux as GNU/Linux, which makes sense given that Linux is only a kernel, whereas most of Linux's functionality comes from the GNU Project. This is a massively over-argued topic with lots of flaming, and people seem to take it more seriously than you would first imagine.
Roughly speaking, (you really should do a lot more reading yourself before you try to comment on this topic) the Linux kernel supports a variety of operations - running programs, handling input and devices, etc. The GNU tools allow users to interact with the kernel.
ls? Yup. gcc? Yup. chmod, ld, wget, bash, emacs, locate, tar, diff? All GNU. Even GNOME is GNU. Even glibc is GNU. While certainly not everything is GNU, it's fair (and technically correct) to say that Linux would not be an operating system if it weren't for the Free Software Foundation and GNU, and why we refer to the 'Linux kernel' and the 'GNU/Linux operating system'
An alternative opinion is that if you are going to call it GNU/Linux, there are other important projects that should get a byline. What about X for example, which for most people is pretty important. Never mind programs that also form part of the core functionality of the system, e.g. sendmail, Perl, Apache etc. However, this opinion is usually derided on the grounds that you can opt not to install any of those programs and still use GNU/Linux with little difference (or you could use Postfix, Python, etc), whereas trying to operate a system that has none of the standard C calls, no compiler, no libraries, no basic tools to allow you to even create a directory, etc, would leave you more than just a little short of a working operating system.
The argument that if Linux is to be called GNU/Linux, it should therefore be called KDE/GNU/X/Linux is therefore somewhat spurious - Linux users have the choice to use other X-like implementations or indeed (as is still popular, especially in the server environment) to run no graphical environment at all, whereas GNU is ubiquitous and mandatory.