Lesson 1 · Computational Thinking
Bugs are normal — and findable.
In 1947, a computer at Harvard stopped working. Engineers opened it up and found a moth stuck inside. They taped it into the logbook and wrote: "First actual case of bug being found."
The name stuck. Today a bug is any mistake that makes a program behave differently from what you intended.
Here's the part nobody tells beginners: every programmer writes bugs. Every day. Professionals with twenty years of experience write them constantly. The difference is not that they avoid bugs — it's that they find them quickly and calmly.
When something goes wrong, it feels like the computer misbehaved. It didn't.
The computer followed your instructions perfectly. Your instructions were wrong.
That sounds harsh, but it's actually the most encouraging fact in programming: if the mistake is in your instructions, then it's findable, and it's fixable. A computer that randomly did its own thing would be impossible to work with.
So the question is never "why is it broken?" It's "which of my instructions doesn't say what I meant?"
5 more parts in this lesson
Walkthroughs, code labs, mini-games and the checkpoint quiz unlock when you buy the course.