How to Take Screenshot on a Mac

1. You can use key shortcuts

Shift + Command + 3 – take a shot of a full Desktop screen.
Shift + Command + 4 – take a screenshot of a certain area (choose with a mouse) of your Desktop.
Shift + Command + 4 + Space – take a screenshot of a certain window of the Desktop.
Shift + Command + 3 + Control – save a screenshot of a full Desktop to the Clipboard.
Shift + Command + 4 + Control – save a screenshot of a certain area (choose with a mouse) to the Clipboard.
Shift + Command + 4 + Space + Control – save a screenshot of a certain Window to the Clipboard.

2. You can use the default Apple app - Grab

Find it via Spotlight or in the Launchpad.

Also, you can change screenshots settings using the Terminal commands.