If we talking about computers essential part of any pc is operating system.Operating system is important for any devices but for pc/mac there's only 3 main operating systems.
(one of many essentials is operating system,picture source bing)
DOS, Windows, or Linux.
DOS operating system stands for Disk Operating System, which is an operating system that was popular till 1995 in IBM PCs. It's a single- tasking zilches i.e., it can perform one task at a time. 
(ms dos,source bing)
It's grounded on a command- line interface where one has to give instructions to the computer in the command form. It runs from hard disks, droopy disks, or any other storehouse bias and therefore provides an terrain for the prosecution of programs. It occupies lower memory.
To use further than 64kb of memory, memory extenders were used, which aged Windows used to use further memory. It was firstly released only to OEMs( Original Equipment Manufacturers) who added support for their tackle. It was ultimately released to the public. 
(evolution of windows, source google)
Windows operating system is a product of Microsoft. It's an operating system with colorful performances, Windows 10 being the rearmost interpretation. It's a Graphics- Grounded stoner interface. druggies give commands through clicking or choosing icons and images with the help of a mouse, keyboard, or touchscreen to the computer. Windows was firstly a DOS extender running on top of DOS. 
(windows 10 logo,source Google)
The Windows 9x family conforming of Windows 95, Windows 98, Windows 98SE, and Windows ME ran on top of MS- DOS and is able of running DOS programs directly. Windows NT was released independently and is movable , and originally, it was written in C and C languages where processor competence ability is separated into DAL and HLL and was designed to be more secure than DOS and the Windows 9x family.
The Windows NT family includes Windows NT3.x,4.x, Windows 2000, Windows XP, Windows Vista, Windows 7, and so on. Windows is definitely lot more dependable than DOS and handles any error smother and with ease due to colorful tools available for debugging and error running.
Linux operating system is a freely distributed multitasking and (multi-user) operating system that behaves like UNIX. It was firstly developed by a Finnish pupil/student, LINUS TORVALDS in 1991. 
(Linux logo,source Google)
