What Is Debugging? How to Find and Fix Bugs in Code

Debugging is the process of finding and fixing errors — called "bugs" — in a computer program so that the code runs the way it is supposed to. Every programmer, from a child building their first Scratch game to a professional software engineer, debugs constantly. Writing code and fixing it are two halves of the same skill.

How Debugging Works

Debugging usually follows a simple loop: run the program, notice that something is wrong, track down the line or block causing the problem, fix it, and test again. The word "bug" dates back to 1947, when computer scientist Grace Hopper and her team found a real moth trapped inside a Harvard Mark II computer and taped it into their logbook as the "first actual case of a bug being found."

Imagine a child builds a Scratch game where the cat sprite is supposed to move when the arrow key is pressed — but it stays perfectly still. The bug might be a missing "when key pressed" block, or a movement set to 0 steps. By checking each block one at a time, the child spots the mistake and the sprite finally walks. Studies suggest programmers spend up to 50% of their time debugging, so it is a normal part of coding, not a sign of failure.

Why It Matters for Kids

Debugging teaches children to stay calm, think logically, and keep trying when something does not work — the same persistence prized in Malaysia's KSSR curriculum and STEM education. Instead of giving up, kids learn to break a problem into small steps and test their ideas one by one. Structured Algonova coding classes guide children through this process, and our guide on what coding is for kids explains the bigger picture.

Curious how your child debugs their very first program? A free trial lesson is a simple place to begin.