Chapter Two · Part 1: The Machine

The Operating System

In Chapter 1 the desktop was the last step of turning the computer on. This chapter is about what loaded just before it: the one large program that runs the whole machine, and what it does for you every second you use it.

4 topics

When you pressed power in Chapter 1, the last thing to load was the operating system — the program that takes charge of the machine and stays running until you shut down. You never see it directly; you see the desktop, the apps, and the files it puts in front of you. This chapter is about the layer doing that work.

Four topics build it up. First, what an operating system actually is and where it sits — between your apps and the bare hardware. Then the idea of a process, a single program the operating system is currently running, and how it keeps dozens of them going at once. Then the system underneath your files and folders. And finally, how the computer knows who you are and decides what you're allowed to do — the quiet starting point of all computer security.

What the operating system manages, across this chapter

Programs

It runs each open app as a process and quietly shares the processor between all of them, switching so fast they all seem to run at once.

Files

It organizes everything you save into folders on the disk, and finds any file by its path.

Access

User accounts and permissions decide who is allowed to open, change, or delete what.