The operating system is the computer program which manages the computer hardware and software resources, and also the kernel and cornerstone of the computer system.

For me, I know some operating systems such as Windows, Mac OS and so on. 

As for Windows, Microsoft Windows series operating system is a graphic operating system based on ms-dos designed by Microsoft for IBM machines. Modern Windows systems, such as Windows 2000 and Windows XP, were created in the modern Windows NT kernel. The NT kernel was borrowed from OS/2 and OpenVMS. Windows can run on 32-bit and 64-bit Intel and AMD processors, but early versions can also run on DEC Alpha, MIPS, and PowerPC architectures.

For Mac OS, formerly known as "macOS X" or "OS X," is an operating system that runs on apple's Macintosh computers. Mac OS was the first successful graphical user interface system in the commercial world. Macintosh developers included Bill Atkinson, Jef Raskin and Andy Hertzfeld. Starting with OS X 10.8, remove the Mac from the name and keep only the OS X and version number. On June 13, 2016 at WWDC2016, apple changed the name of OS X to macOS. The current version of OS X is 10.14, or macOS Mojave.