Linux is a free computer operating system that was created by Linus Torvalds in 1991 and has grown from contributions from software developers all over the world. Fedora Core and Red Hat Enterprise versions of Red Hat Linux are distributions of Linux that package together the software needed to run Linux and makes it easier to install and run.
Features in Red Hat Linux distributions include a simplified installation procedure, Red Hat Package Management (RPM) tools for managing the software, and easy-to-use GNOME and KDE desktop environments. You can get Red Hat Linux from the Internet or from distributions that come with books such as this one.
Linux is based on a culture of free exchange of software. Linux's roots are based in the UNIX operating system. UNIX provided most of the framework that was used to create Linux. That framework came in the form of the POSIX standard, which defined the interfaces a UNIX system needs to support in order to be a UNIX system.