Linux at its core is a kernel, the central driving force of an operating system that allocates resources to other aspects of the system. Linux, along with the GNU system (which is closely associated with Free Software Foundation) are now collectively referred to as GNU/Linux, and make up a complete operating system which is widely used today by millions across the world. To read more about the history of the GNU project and Linux, see this article.
The free software philosophy is about an open and shared operating system which is not just free as in money, but free as in freedom. The GNU/Linux operating system gives users more control over their computing experience than competing operating systems such as Windows, which could contain also malicious features unknown to their users.
What's all this about distributions?Edit
There are several distributions of GNU/Linux, the easiest to begin with being Linux Mint . Other variants of Linux Mint exist, a popular being Linux Mint Debian, which is based on the Debian system, which aims to be the most freedom respecting operating system available. A further list of recommended operating systems are categorized as follows
Easy to use and install
Gentoo Linux (to the point of being a joke)
/g/'s Favourite picks