To take a screenshot on a Mac, use these keyboard shortcuts:

• Press Shift + Command + 3 to capture the entire screen. The screenshot will be saved to your desktop.
• Press Shift + Command + 4 to turn the cursor into a crosshair, then click and drag to select a portion of the screen to capture.
• Press Shift + Command + 4, then press the Spacebar to capture a specific window. The cursor will change to a camera icon, so click the window you want to screenshot.
• Press Shift + Command + 5 to open the Screenshot app with various options: capture entire screen, a selected window, or a selected portion, and also options for screen recording.
• For MacBooks with a Touch Bar, press Shift + Command + 6 to screenshot the Touch Bar.

After taking a screenshot, a thumbnail may appear in the bottom-right corner for quick editing or sharing. If ignored, the screenshot will save automatically to the desktop by default.