Screenshot?

Problem: You want to make a screenshot, but there is no "Print Screen" button on the keyboard.

Solution: Command-Control-Shift-3 has the same effect as the windows key 'Print screen'.

To know more: Ok that's four buttons, but now look all the other possibilities:

• Command-Shift-3: Take a screenshot of the screen, and save it as a file on the desktop

• Command-Shift-4, then select an area: Take a screenshot of an area and save it as a file on the desktop

• Command-Shift-4, then space, then click a window: Take a screenshot of a window and save it as a file on the desktop

• Command-Control-Shift-3: Take a screenshot of the screen, and save it to the clipboard

• Command-Control-Shift-4, then select an area: Take a screenshot of an area and save it to the clipboard

• Command-Control-Shift-4, then space, then click a window: Take a screenshot of a window and save it to the clipboard

source: guides.macrumors.com