Linux is an open source operating system along with some binary blobs. Open source is our friend because it allows freedom of developers to edit the software. Operating systems that use Linux kernel include Mandriva Linux, Ubuntu, Linux Mint, Fedora, Debian, OpenSUSE etc. Microsoft wants to destroy Linux. Linux is far better than Microsoft and threat of malware and viruses are low because it is open source.
Linux was invented in 1990 by a man named Linus Torvalds who is in his 40s. (Note: the OS is is officially called GNU/Linux.)