Certain key combinations allow you to do things that normally need a mouse, trackpad, or other input device. Using keyboard shortcuts can save you valuable time, making you more productive.
Below are some must-know shortcuts to help make you more productive.
Command-W: Close the front window. To close all windows of the app, press Option-Command-W.
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.
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.
Option-Command-Esc: Force quit an app.
Command–Space bar: Show or hide the Spotlight search field.
Command-Tab: Switch to the next most recently used app among your open app.
Command-D: Duplicate the selected files.
For more shortcuts: https://support.apple.com/en-us/HT201236