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.dmg, .pkg, .app Explained
| File Type | What It Is | What to Do |
|---|---|---|
.dmg | Disk image (a virtual drive) | Double-click → drag app to Applications → eject the image |
.pkg | Installer package | Double-click → follow the wizard (installs system components) |
.app | The app itself | Drag to Applications folder. Done. |
.zip | Compressed archive | Double-click → extracts the .app. Move it to Applications. |
The #1 Mistake
Running an app directly from the .dmg without dragging it to Applications. The app works but behaves strangely: no preferences saved, updates fail. Always drag to Applications first.