GNU is the userland, applications like text editors, compilers, the user interface and so on. It is truly not Unix, because although it follows Unix conventions, it does not re-use any Unix code. However, it is possible for a GNU system to INCLUDE actual Unix, in the form of the kernel. The most common version of GNU is GNU/Linux, that is the GNU userland combined with the Linux kernel. Linux is not part of GNU, but likewise is Unix-like without using any actual original Unix code. However, there is such a thing as GNU/kFreeBSD, that is the GNU userland combined with the kernel from FreeBSD, FreeBSD being actual real Unix, as it is a development branch of the original Unix operating system from the 1970s, rather than a reimplementation from scratch like Linux is. So technically, a GNU/kFreeBSD operating system does include some real Unix code, however it does not invalidate the GNU acronym, since GNU is the userland, not the entire operating system. It wouldn't be entirely accurate to label it as a Unix operating system either, as the numerous userland utilities that come with most distributions of Unix have been replaced with their GNU equivalents. It may therefore be regarded as a fusion of Unix and non-Unix (GNU).