When there is an error on your computer, it is helpful to be able to show what you see. You can capture the images on your computer screen to show someone else the error message or give visual examples of how to do something.
In Windows, use the Print Screen key (normally on the top right hand side of the keyboard) to copy the screen image into a graphic. It will go onto your invisible Clipboard, then you can paste it into an email or other type of program, such as Word. You can also use the Alt Print Screen key, which copies only the window.
On the Mac, press Command-Shift-3. (Command is the key with the propeller on it, next to the Space bar.) You’ll hear a snapshot sound, and you get a graphics file on your desktop—a picture of the entire screen image. If you press Command-Shift-4 instead, you get a crosshair cursor. You can draw across just one portion of the screen. Or, if you now tap the Space bar, you turn the cursor into a little camera icon. You can now click on just one window or toolbar that you want to copy.