Introduction
Your program keeps creating objects. Every function call, every loop iteration, every parsed JSON response produces new ones. You don't manually delete most of them. You've never written a line of code that says "free this memory now." And yet your application doesn't immediately exhaust all available RAM and crash.
So who cleans everything up?
The answer is a garbage collector, a piece of the runtime that runs quietly in the background, deciding what your program no longer needs and reclaiming that memory for future use. Most developers interact with it only when something goes wrong: an unexpected pause, a memory leak, or an out-of-memory error that shouldn't be happening.
Understanding how it actually works turns those confusing moments into solvable problems. And as a bonus, the core algorithm is simple enough to build yourself. We'll do that by the end of this article.
