Linux is a family of Unix based operating systems. It is open source software that allows for any modification, use and distribution. Its creator Linus Torvalds made a huge contribution to the development of Linux systems. It is also the most widely used operating system on servers and mainframes. At the same time, it is the most stable and secure operating system - it is used by Linux, among others NASA, SpaceX or AWS. Linux currently comes in many varieties and distributions and is a symbol of the Open Source community.