What is an Operating System?
Before Linux makes sense, you need one idea: what an operating system actually does.
Right now, your computer is doing dozens of things at once: showing this page, playing your music, checking for messages, keeping the clock ticking.
But a computer's processor can't organise any of that by itself. It's just a chip that follows instructions. So who decides which program gets to run, which one gets memory, and which one is allowed to touch your files?
A special program that starts the moment you power on and never stops: the operating system (OS for short) — the manager program that runs all your other programs.
Think of a computer as a busy hotel:
- The hardware (processor, memory, disk, screen) is the building itself
- Your programs (browser, music player, games) are the guests
- The operating system is the hotel manager
The manager decides who gets which room (memory), keeps guests out of each other's rooms (security), and passes requests to the building's services ("guest 12 wants to print something").
You already know some operating systems by name: Windows, macOS, Android, and iOS are all operating systems. Linux — the one this course is about — is another.
Using the hotel picture: your music player wants to save a playlist file to the disk. What actually happens?
- AThe music player asks the operating system, and the OS writes the file to disk
- BThe music player writes directly to the disk hardware
- CThe processor saves the file on its own
- DFiles can only be saved by the operating system's own programs
Which of these is an operating system?
- AAndroid
- BGoogle Chrome
- CMicrosoft Word
- DYouTube
Here's the part that makes this course matter.
The websites and apps you use don't live in your laptop — they live on servers: computers in data centers that run 24 hours a day, answering requests from millions of people.
Servers are computers, so they need an operating system too. And the operating system that the vast majority of them run is Linux.
When you send a message, stream a video, or check your bank balance — somewhere, a Linux machine did the work.
A server is best described as…
- AA computer that runs continuously to answer requests from other computers
- BA more powerful kind of monitor
- CA program that only runs on Windows
- DAnother name for the internet
- An operating system (OS) is the manager program that runs all other programs and shares the hardware between them
- Programs never touch hardware directly — they ask the OS, which enforces the rules
- The kernel is the OS's core, the part that talks to hardware
- Windows, macOS, Android, iOS, and Linux are all operating systems
- Servers — the always-on computers that power every app and website — overwhelmingly run Linux
Next: what Linux actually is, where it came from, and why it quietly took over the world.