- Linux originated as a clone of the UNIX operating system. Key developers included Linus Torvalds and developers from the GNU project. - Linux is open source, multi-user, and can run on a variety of hardware. It includes components like the Linux kernel, shell, terminal emulator, and desktop environments. - The document provides information on common Linux commands, files, users/groups, permissions, and startup scripts. It describes the Linux file system and compression/archiving utilities.