Command-X: Cut the selected item and copy it to the Clipboard.
Command-C: Copy the selected item to the Clipboard. This also works for files in the Finder.
Command-V: Paste the contents of the Clipboard into the current document or app. This also works for files in the Finder.
Command-Z: Undo the previous command. You can then press Shift-Command-Z to Redo, reversing the undo command. In some apps, you can undo and redo multiple commands.
Command-A: Select All items.
Command-F: Find items in a document or open a Find window.
Command-G: Find Again: Find the next occurrence of the item previously found. To find the previous occurrence, press Shift-Command-G.
Command-H: Hide the windows of the front app. To view the front app but hide all other apps, press Option-Command-H.
Command-M: Minimize the front window to the Dock. To minimize all windows of the front app, press Option-Command-M.
Command-O: Open the selected item, or open a dialog to select a file to open.
Command-P: Print the current document.
Command-S: Save the current document.
Command-T: Open a new tab.
Command-W: Close the front window. To close all windows of the app, press Option-Command-W.
Option-Command-Esc: Force quit an app.
Command–Space bar: Show or hide the Spotlight search field. To perform a Spotlight search from a Finder window, press Command–Option–Space bar. (If you use multiple input sources to type in different languages, these shortcuts change input sources instead of showing Spotlight. Learn how to change a conflicting keyboard shortcut.)
Control–Command–Space bar: Show the Character Viewer, from which you can choose emoji and other symbols.
Control-Command-F: Use the app in full screen, if supported by the app.
Space bar: Use Quick Look to preview the selected item.
Command-Tab: Switch to the next most recently used app among your open apps.
Shift-Command-5: In macOS Mojave or later, take a screenshot or make a screen recording. Or use Shift-Command-3 or Shift-Command-4 for screenshots. Learn more about screenshots
Shift-Command-N: Create a new folder in the Finder.
Command-Comma (,): Open preferences for the front app.