taking screenshots or screencopies from mac os x without additional software

http://docs.info.apple.com/article.html?artnum=61544

To take a picture of the whole screen, press Command-Shift-3.

To take a picture of part of the screen, press Command-Shift-4 and drag to select the area you want.

The picture is saved as a TIFF file on your Desktop. Note: Mac OS X 10.2 and later saves pictures as PDF files. See document 107078 "Mac OS X 10.2: Screen Shots Are Saved in PDF, May Be Converted" for additional information.

To copy the screen capture to the Clipboard instead of saving it as a file, press Control-Command-Shift-3 to copy the entire screen to the Clipboard, or Control-Command-Shift-4 to copy the selected range to the Clipboard.


or even more deatil at:
http://guides.macrumors.com/Taking_Screenshots_in_Mac_OS_X