Linux is an open source operating system inspired by UNIX. It is the dominate operating system for cloud computing. There are many flavors (aka distributions) of Linux, but the main ones are Ubuntu, Debian, RedHat, CentOS, SuSe. A new generation of micro distributions include Alpine Linux and BusyBox. There are also cloud-native OSes like CoreOS, Project Atomic, Snappy, and Rancher OS.