Windows Print Screen Key
Print screens goes to your clipboard, a temporary memory windows use to hold data (mainly used for copy/paste, when you copy a text or file windows stores the text or file in the clipboard memory and makes it available when you paste it to some place).
When u press printscreen windows puts the picture in the clipboard much like when you use copy/paste. just open any program (paint, wordpad, etc) and use the paste command (CTRL-V) and your picture will come)
Note: you can store only one picture (or any other data) at a time in clipboard.
You can launch c:\windows\system32\clipbrd.exe which will show you what is currently stored and allows you to save it.
Copied from Pirate Galaxy Main Forum.