Capturing a screen image is a basic computing task — so basic, in fact, that almost every computer keyboard has a dedicated key to grab a picture of what the monitor is displaying in the instant the key is pressed. Three Linux apps have proven very useful to me. I use Shutter, Gnome Screenshot and mtPaint Snapshot almost daily in documenting Linux Picks selections and feature articles about using computers. In the earliest text-based DOS days of the PC, the Print Screen key was used to literally send the image on the monitor’s display to the printer.
Read more at LinuxInsider