Module 1 · Introduction to Programming · Lesson 1 of 7

How a computer program works

A program is nothing more than a list of instructions. The computer reads them one at a time, from top to bottom, and does exactly what each one says — no guessing, no skipping ahead. Watch this tiny program run: the highlight is the computer's place in the code, and the panel on the right is what it produces.

print("Hello!")
print("Welcome to loop")
print("Let's begin")

Each line above is a single instruction — print(...), which shows text on screen. The computer runs the first, then the second, then the third, always in that order. It feels instant because a processor runs billions of these steps per second, but the rule never changes: one instruction after another.

Everything else you'll learn — decisions, loops, functions — is just a way of controlling which instructions run and how many times. But underneath, it's always this: a sequence of steps the computer follows faithfully.