Both the Mac OS and Windows operating systems make it easy to take screenshots. Just use the following keyboard shortcuts to capture the current screen displayed on your computer:
Mac OS X:
Command-Shift-3: Saves a screenshot of the entire desktop to an image file on the desktop.
Command-Shift-4: Saves a screenshot of a selection selected with the cursor to an image file on the desktop.
Command-Control-Shift-3: Saves a screenshot of the entire desktop to the clipboard.
Command-Control-Shift-4: Saves a screenshot or a selection selected with the cursor to the clipboard.
Windows XP:
Print Screen: Saves a screenshot of the entire desktop to the clipboard.
Alt+Print Screen: Saves a screenshot of the active window to the clipboard.