Linux Kernel was born in 1990s and it is based on Unix, but it is developed under GNU license, meaning that it is 100% free and the code is available to anyone and it can be freely modified. There are Linux operating systems for servers and clients, a wide variety of Linux distributions, desktop OS and tools. Red Hat or SUSE Linux are some examples of server systems and Debian, Ubuntu or Linux Mint are desktop OS.
Much of the success of technological evolution goes through virtualization. A concept that, outside the technical world, is becoming more widespread. It hides a power that, up to now, we have only timidly begun to explore.