Operating system is an interface between the user and the hardware, just as a teacher has blackboard as an interface between student and herself.
DOS(Disk Operating System) was the first OS developed by Microsoft, but it had only keyboard as an input device and it was single user system. Later Windows 3.1 came into existence which was GUI(Graphical User Interface).(i.e)Mouse came into existence with keyboard. In order to be familiar with mouse the first application was paint with Windows 3.1 then later Word, Excel, Powerpoint came into existence. Later Windows 95 an upgraded version of windows was launched. After the Windows 98 a new version of windows was launched. Windows 98 was a multitasking system.
Then Windows NT(New Technology) was launched which was multiuser, multitasking and multithreading operating system. Then LINUX came into existence which is multiuser. Linux is open, free operating system. Windows XP, Windows 7, Windows 8 and Windows 10 are the other versions of Windows. Now a days user uses these operating system as per his requirement.