Linux is a free and open-source operating system based on the Linux kernel. It was created by Linus Torvalds in 1991 and has since matured and developed further under itself. Linux can be used on desktops, servers, mainframes, supercomputers, and in devices like Android. It offers advantages like power, stability, low hardware requirements, and free availability from multiple vendors. Popular Linux distributions include Red Hat Enterprise Linux, Fedora, Debian, SUSE Enterprise Linux, and Ubuntu.