Chapter Four · Part 1: The Machine
How Programs Are Made
Every app you open started life as text that a person wrote. This chapter follows that text from the moment someone types it to the moment it becomes a running program — and clears up the tangle of words (software, app, program, application) that all point at roughly the same thing.
So far this course has stayed on the hardware side: you pressed power, the operating system took charge, and a program ran. But none of those programs appeared out of thin air. Someone wrote them. This chapter is about that side of the story — where the instructions a computer follows actually come from.
Four topics trace one path. First, what code is: ordinary written instructions, not magic. Then why there are hundreds of different languages to write it in. Then the translation step that turns that written text into something the machine can actually run. And finally, what "software" really means — and why the same thing gets called an app on your phone and a website in your browser, which is the bridge into the second half of the course.