GENERAL
Navigation / Search
COMMAND + SPACE : opens SPOTLIGHT aka the finder tool
COMMAND + TAB : app switcher from left to right
COMMAND + SHIFT + TAB : app swticher from right to left
COMMAND + ~ : switch between pages within same app
COMMAND + L : opens safari search bar
Application Control
COMMAND + , : application preferences
COMMAND + W : close window
COMMAND + Q : shut down any app immediately
COMMAND + OPTION + Q : force app to quit
COMMAND + OPTION + ESC : selects apps to quit
COMMAND + H : hides active window
COMMAND + M : hides active app
COMMAND + O : open
COMMAND + F : find
Screen shots / Screen recording (saved to documents folder)
COMMAND + SHIFT + 3 : entire window
COMMAND + SHIFT + 4 : use mouse to select
COMMAND + SHIFT + 4 then SPACEBAR then tap track pad : open window with shaddow
COMMAND + CTRL + SHIFT + 4 then select some text and its copied to your clip board and then its in the memory to send to someone
COMMAND + SHIFT + 4 then SPACEBAR then press the OPTION key + tap track pad : open window without shaddow
COMMAND + SHIFT + 5 : screenshot + screen RECORDING toolbar
Declutter Desktop
COMMAND + OPTION + : using mouse click on desktop
COMMAND + CTRL + Q : lock screen
FINDER/FILES
select file then hit SPACE : previews first page of file
you can do this with multiple files and use COMMAND + Y to flick through them