All these keyboard shortcuts are composed of a combination of several keys whose name or appearance may differ depending on the age of your machine.

– Command + N: Open a new Finder window

– Command + Shift + N: Create a new directory in the Finder

– Command + I: Displaying the information of an element

– Command + D: Duplicate the selected elements.

Note that when you are saving a document from an application, this shortcut allows you to choose the Desktop as the saving destination.

– Command + T: Open a new tab in the Finder, a web browser

– Command + Q: Exit (Close) an application

– Command + Tab: Switch from one open application to another

– Command + H: Hide the active application window

– Command + Option + H: Hides all active windows except the one in the foreground

– Command + M: Minimize the active window in the dock

– Command + Option + M: Minimize all windows of the active application, except the one in the foreground

– Command +, (comma) : Display the parameters of the active application

– Command + Option + D: Show or hide the Dock

– Command + Delete: Place one or more elements directly in the recycle bin

– Shift + Command + Delete: Empty the contents of the recycle bin

– Control + lateral directional arrows: Switch from one desktop to another

– Space bar or Command + Y: display a preview of the selected file

– Command + Space: Display the Spotlight search field

Option + Command + Esc: Force a blocked application to close 

Source :01net.com

All these keyboard shortcuts are composed of a combination of several keys whose name or appearance may differ depending on the age of your machine.

– Command + N: Open a new Finder window

– Command + Shift + N: Create a new directory in the Finder

– Command + I: Displaying the information of an element

– Command + D: Duplicate the selected elements.

Note that when you are saving a document from an application, this shortcut allows you to choose the Desktop as the saving destination.

– Command + T: Open a new tab in the Finder, a web browser

– Command + Q: Exit (Close) an application

– Command + Tab: Switch from one open application to another

– Command + H: Hide the active application window

– Command + Option + H: Hides all active windows except the one in the foreground

– Command + M: Minimize the active window in the dock

– Command + Option + M: Minimize all windows of the active application, except the one in the foreground

– Command +, (comma) : Display the parameters of the active application

– Command + Option + D: Show or hide the Dock

– Command + Delete: Place one or more elements directly in the recycle bin

– Shift + Command + Delete: Empty the contents of the recycle bin

– Control + lateral directional arrows: Switch from one desktop to another

– Space bar or Command + Y: display a preview of the selected file

– Command + Space: Display the Spotlight search field

Option + Command + Esc: Force a blocked application to close 

Source :01net.com