The Linux kernel is widely used now a days to for a usable system, generally what people refer as an OS, which we prefer to call as GNU/Linux distribution. Linux itself is available as a Free Software as well as most of the GNU/Linux Distributions are also available under similar FOSS licenses.
Linux
Linux is an operating system, core kernel or the actual operating system. It was developed by Linus Torvalds. The first prototypes of Linux were publicly released later that year (1991) under the GNU General Public License, designed and drafted by Richard Stallman commonly knows as RMS the free software guru.
With CD/DVD drives almost gone from our systems, the easiest way today to install a new system is via a USB pen drive. This article guides you how to create a bootable pen drive of a Linux ISO image, so that you are able to boot and install from the same.