Press Shift + Command + 3 to capture the entire screen
Press Shift + Command + 4 to capture a selected area
Press Shift + Command + 4, then press Spacebar, then click a window to capture that window
Press Shift + Command + 5 to open screenshot options and capture the screen, window, or selected area
Press Shift + Command + 6 to capture the Touch Bar, if your MacBook has one