Chapter Three · Part 1: The Machine
Different Operating Systems
Almost every computer in the world runs one of three operating-system families — Windows, macOS, or Linux. This chapter walks through what they share, where they differ, and why the one you've probably never used is the one quietly running the internet.
In Chapter 2 you met the operating system — the program that takes over right after you press power and runs everything from then on. But "the operating system" isn't one single thing. The computer you turn on at home almost certainly runs Windows or macOS, while the website you open in your browser is almost certainly served by a third one, Linux, that most people never see.
This chapter sorts out those three. First, what Windows, macOS, and Linux have in common and where they part ways. Then a closer look at Linux — what it is and why servers prefer it — followed by the many packaged versions of Linux called distributions. Last, the two ways you can give a computer instructions: by clicking, the way you already do, or by typing commands, the way engineers often do.