Included as a feature in MacOS, users have the ability to take pictures of either their entire, or simply a portion of, their screen.

In order to take a picture of your entire screen, hold down the Command, Shift and 3 keys:

This will take a picture of your entire screen. The file will then appear on your desktop for you to use.

In order to take a picture of just a portion of your screen, hold down the Command, Shift & 4 keys:

Doing this will cause the cursor to turn into a crosshair . When your cursor takes this shape, left click on the mouse or touchpad and keep it held down. then drag your hand or finger in any direction to see a gray, translucent box take shape. Anything caught within this box will be turned into a picture upon letting go of the left click.

If you would like to view your screenshots in finder, click on the Finder icon on the dock and go to recents. There, you should see all of your recently created screenshots.

Following these steps should allow you to take screenshots on your Mac.