"The only truly secure system is one that is powered off, cast in a block of concrete and sealed in a lead-lined room with armed guards - and even then I have my doubts." - Gene Spafford, Ph.D., Purdue CERIAS
The GNU General Public License
GNU is a recursive acronym for "GNU's Not Unix"; it is pronounced "guh-NEW". Variants of the GNU operating system, which use the kernel Linux, are now widely used; though these systems are often referred to as "Linux", they are more accurately called GNU/Linux systems.The license text is substantial and thus is this linked as plain text here, as Texinfo here or as an appendix in the DocBook format here.