When you mention “Operating System”, most people will think of “Windows” (be it Windows XP, Win 7 or Win 10), “Mac” (in all its recent permutations), or maybe “Android”. And there are plenty of others out there, like “iOS”, “Linux”, and one of the oldest ones, “Unix”.

To be reading this, you’re probably using a application of some kind such as a web browser or app, running on a computer such as tablet, smart phone, laptop, or desktop, by way of an operating system. But what does that all mean? Why does it matter? And why are there so many operating systems? Are they really all so different from one another? Yes? No? Maybe?

To answer these questions, we have to first ponder, what is an operating system? And conversely, what isn’t an operating system?

According to Wikipedia (https://en.wikipedia.org/wiki/Operating_system on 11/1/2015), “An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs. The operating system is a component of the system software in a computer system. Application programs usually require an operating system to function.

And further, “…the operating system acts as an intermediary between programs and the computer hardware“, and as we probably already realize, “Operating systems are found on many devices that contain a computer—from cellular phones and video game consoles to web servers and supercomputers.”

Okay, so we understand from this most enlightened text, that an operating system is a software program that runs on a computer to:

  1. manage the hardware in a computer system;
  2. manage the software running in a computer system;
  3. mediate between the hardware and software.

The Wikipedia article shows this image which can be helpful for us to understand the relationship and function of the operating system in a computer.

Let’s be clear about what these layers are. The “User”? Well, that’s you or I as we interact with a computer.

What about the “Hardware”? Depending on context, that is both the collective whole and the individual parts or components which comprise a computer. Those components include one or more processors (aka “cpu”) and memory (which together are the “brain” of the computer), storage components such as hard disks and dvd readers, networking devices like a wifi or wired ethernet adapter, display elements including the graphics adapter and screen, and input like the mouse, keyboard, mic and camera. Whether a cell phone, tablet, laptop, desktop, or mainframe, they pretty much all share these same kinds of hardware.

“Operating System”? Well, that’s what we’ve been looking at.

“Application”? Simply any “software” program which is executed on “hardware”, usually relying on the “operating system” to interface with hardware when doing things like reading or writing a spreadsheet, browsing the internet, or playing a music file. These include, of course, a web browser, word processor, calculator, or mp3 playback program.

So far, so good. We now understand that an operating system acts as an intermediary between hardware and applications. Let’s take a break here and in the next installment, discuss something that’s missing so far, which is the “what” for how the user interacts with the operating system and applications.