Pressing the <PrtScn> key copies the entire display to the
clipboard. Pressing <ALT>+<PrtScn> copies only the active Window to
the clipboard (iow, into RAM). To view the screen capture, open a
graphics program, such as MS Paint, and press <CTRL>+V. This will
paste the contents of the clipboard (your screenshot) into the open
file, and allow you to view it or save it as a file for later use.