Operating System

An operating system is the program that makes a device usable in the first place. Windows, macOS, Android, iOS, and Linux are the best-known examples. It is the first thing to start when you press the power button, and it then runs continuously in the background. Its job is to mediate between the hardware and all other programs. Hardware here means the components you can physically touch: processor, memory, screen, keyboard. Without an operating system, a computer would be a collection of electronics that nobody could do anything with.

Why no program can do without an operating system

Imagine an office building without a building management. Every company would have to connect its own power, allocate rooms, and control the elevator itself. That is exactly the role the operating system plays for the programs on your device. A word processor doesn’t need to know exactly how your hard drive works. It tells the operating system “save this file,” and the operating system takes care of the rest.

This makes it possible to run the same app on very different hardware. A game runs on a laptop from 2019 and on a brand-new device, even though both have completely different components. The operating system smooths out these differences. That’s also why it’s so hard to port a program from Windows to macOS: the mediation layer is a different one.

Operating systems are also an enormous factor of economic power. Whoever controls the operating system determines which apps are allowed to be installed and who gets to profit from them. This is exactly what many antitrust proceedings against Apple and Google revolve around. The App Store is not a technical necessity, but a decision made by the operating system provider.

Kernel, drivers, and the division of processing time

The core is called the kernel, roughly meaning “core” or “nucleus.” It is the part that has direct access to the processor and memory. All normal programs run on top of it, and they are only allowed to do what the kernel permits them to do. This separation is a security principle: if an app crashes, it doesn’t take the whole device down with it.

A second core task is distributing processing time. Your processor can only do a limited number of things at once. Yet browser, music app, and email program appear to run in parallel. In reality, the operating system switches between them many times per second. This switching happens so fast that it looks like simultaneity to you.

For contact with individual devices there are drivers. These are small auxiliary programs that explain, for example, how a particular printer is addressed. A common misconception is to confuse the operating system with the visible interface. Windows, icons, and menus are just the façade. The actual operation happens invisibly underneath.

From smartphone to AI data center

You use several operating systems every day without thinking about it. Your phone runs Android or iOS, school computers mostly Windows. The router at home, a car, and a TV also have one. There it’s usually a stripped-down variant of Linux that nobody perceives as such.

In the data centers where AI models are trained, Linux dominates almost completely. It’s free, open-source, and can be adapted for specialized hardware. When news talks about servers and the cloud, it’s almost always Linux behind it. Cloud here simply means that the computers are located in someone else’s data centers and are used over the internet.

More recently, the term has also appeared as a comparison. Some companies call their AI assistants an “operating system for work.” What’s meant is that the AI sits like a mediation layer between the user and many individual programs. Technically, that’s not an operating system, but marketing with a fitting image.