Linux (/ˈlɪnʊks/, LIN-uuks)[15] is a family of open-source Unix-like operating systems based on the Linux kernel,[16] an operating system kernel first released on September 17, 1991, by Linus Torvalds.[17][18][19] Linux is typically packaged as a Linux distribution (distro), which includes the kernel and supporting system software and libraries—most of which are provided by third parties—to create a complete operating system, designed as a clone of Unix and released under the copyleft GPL license.