Linux is an open-source operating system based on Unix. It is robust, scalable, stable, and secure. Linux was originally developed in 1991 by Linus Torvalds and is freely available. Common Linux distributions include Red Hat, Debian, SUSE, and Gentoo. When installing Linux, important steps include identifying compatible hardware, determining the installation method, configuring partitions, and selecting packages to install based on the intended use of the system.