Linux is Family of free and opensource operating Systems Based on Linux Kernel.
Linux kernel is Created By by Linus Torvalds, first released on September 17, 1991 Linux kernel is written in C Computer programming language. Linux is part of opensource Software
Linux kernel was first created for Personal Computers based on Intel x86 architecture but now it is powering number of devices Including android devices based on arm architecture to embed devices and servers , Chromebooks and many others .
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word “Linux” in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Nowadays more than there are 600 Linux Distributions available some popular distributions are Debian , Arch Linux ,Gentoo Linux You can find many more on Distro watch every Linux Distribution had own purpose for example Ubuntu Server and Open SUSE is for servers .
You can know more about Linux on Opensource.com wikipedia and Linux.com