for Mac and Windows Users
Need to take a picture of your screen without using any additional software? Here are quick key commands that will take a snapshot of your desktop or open window.
Mac OS 9/X:
Press Cmd+Shift+3 to capture the entire screen.
Press Cmd+Shift+4, then click and drag to select the portion of the screen you want to capture.
Mac OS X only:
Press Cmd+Shift+4, then press the Space bar and highlight the open window or dialog box you want to capture.
Microsoft Windows
Press the PrintScrn key to capture the entire screen to the clipboard.
Paste the clipboard into a document.
Press ALT+PrintScrn to capture the active window or dialog box to the clipboard.
Paste the clipboard into a document.