Mac tip: add Control to any screenshot shortcut and the capture goes to your clipboard instead of a file on your desktop.
Shift-Control-Command-4: an area
Shift-Control-Command-3: the whole screen
Then paste it straight into Mail, Slack or Notes. Apple documents it here: https://support.apple.com/en-us/102646
Apple SupportTake a screenshot on Mac - Apple SupportYou can capture the entire screen, a window, or just a portion of the screen.