Operating system is the single most important application that manages resource and memory allocation and schedules tasks. They come preloaded in computers. The Operating system loads into the memory and runs every time a computer is booted. Most modern Operating systems use Graphical User Interface. With GUI, the user can interact with the computer by clicking menu buttons, icons on screen. There are three main types of OS for personal computers.

-- Microsoft Windows: Windows comes preloaded in most PCs. There are many versions and the most recent version is Windows 11. Windows, created by Microsoft, is one of the most popular and easy to use operating systems today. Windows accounts for about 80% of the world wide OS market.

-- MacOS: It is an operating system created by Apple that works on all Macintosh computers. Some of the versions of MacOS include Mojave and Sierra. MacOS accounts for 10% of all Operating systems. MacOS are designed to specifically work only on Apple computers.

-- Linux: They are a line of open source operating systems, which can be loaded and used by anyone for free. Linux can be modified by anyone unlike Windows and MacOS that are modified by the company that owns them. Some common Linux OS include Ubuntu, Debian, Fedora. Linux based OS is used in Chromebooks, which is popular in the K-12 market.