Press Command (⌘) + Shift + 3 to capture the entire screen
Press Command (⌘) + Shift + 4 to select an area to capture
Press Command (⌘) + Shift + 4, then press and hold Space to capture a window
Press Command (⌘) + Shift + 5 to open the screenshot toolbar (select options from there)
Press Control + Command (⌘) + Shift + 3 to capture the entire screen to the clipboard
Press Control + Command (⌘) + Shift + 4 to capture a selected area to the clipboard
Press Control + Command (⌘) + Shift + 4, then press and hold Space to capture a window to the clipboard