Which keyboard shortcuts are the best to save time and improve productivity? [closed]

Other than cut, copy, paste, etc. which keyboard shortcuts do you frequently use that save time and improve productivity?

Here are some of the handy shortcuts that I use:

1. Command + M: Minimizes the current/top application window into the dock
2. Command + Space: Shows spotlight
3. Command + Option + D: Hides/shows the dock
4. Command + Shift + T: Opens your last closed tab when you are in a browser
5. Command + Shift + 3: Takes a full-screen screenshot, then saves picture to desktop (add Control if you want to copy to clipboard)
6. Shift+Command+Q: Logs out of current mac account