1. The App Bundle Myth
Many Mac users believe that dragging an application from /Applications to the Trash completely removes it. In reality, macOS applications generate substantial persistent data across user and root library directories during initial launch and usage.
2. Where Leftovers Live in ~/Library
~/Library/Application Support/<App>: Offline databases, Chromium profiles, Electron assets.~/Library/Caches/<BundleId>: WebKit network caches and cached textures.~/Library/Preferences/<BundleId>.plist: License tokens and user preferences.~/Library/Containers/<BundleId>: Sandboxed virtual home directories.