How a computer works

Four lessons with no code, from the electrical switch to files and paths: what someone who never opened a terminal needs before the first command.

From electricity to bitsEverything in a computer, from a photo to a word to a game, is made of tiny electrical switches that are either open or closed. This lesson shows how electricity becomes a number, and a number a letter.
The processor, memory and diskThree parts make a computer: one that calculates, one that remembers while the machine is on, and one that keeps things after it is off. Here you learn why a machine slows down and why unsaved files vanish.
The operating system and the programBetween your program and the hardware stands the operating system: it shares the processor among programs, protects each one's memory, and opens files on their behalf. Here you learn what a process is, and why you keep hearing the word Linux.
Files, folders and pathsBefore your first command you need to know what a file really is, how folders arrange themselves as a tree, and how a path describes where anything sits in one line.