macOS Storage settings shows a vague bar with a giant "System Data" bucket. Here is what is actually in there, how to find the real culprits yourself, and why a proper disk map saves you an afternoon of guessing.
Dragging an app to the Trash only removes the bundle. The caches, preferences, support files and containers it scattered across your Mac can linger for years — and most people never know they are still there.
You cleared those caches last month. They came back — and they brought friends. The real story is not the size on any given day; it is how fast it grows, and which tool is driving it.
node_modules, Docker images, DerivedData, Homebrew downloads — developer caches balloon silently and never clean up after themselves. Here is how to find what is eating your disk, and how to track it over time instead of playing whack-a-mole.