Linux is free and open source UNIX type Operating System initially created by Linux Tovrvalds developed under GNU ( General Public Licence) and the source code is freely available to every one.
In Brief Description
Linux is a freely distributed implementation of a UNIX-like kernel, the low level core of an operating system. Because Linux takes the UNIX system as its inspiration, Linux and UNIX programs are very similar. In fact, almost all programs written for UNIX can be compiled and run on Linux.
Linux was developed by Linus Torvalds at the University of Helsinki, with the help of UNIX programmers from across the Internet. It began as a hobby inspired by Andy Tanenbaum’s Minix, a small UNIX like system, but has grown to become a complete system in its own right. The intention is that the Linux kernel will not incorporate proprietary code but will contain nothing but freely distributable code.