It’s often useful to capture a portion of the screen to paste into a document or for later use. Mac OS X lets you do that with Cmd-Shift-3 for the entire screen (useless IMHO) or a portion of the screen with Cmd-Shift-4 (very useful!). This latter option creates a .png or a .jpg, depending on which one you choose.
To learn how to change your default screen capture keyboard shortcut to a more convenient key combination, or to use Grab (free on your Mac), or better yet SnapNDrag, a free app, help yourself to the HMAUS handouts at http://public.me.com/hmauscloud. Click the MacLearn link, then the Screen Capture folder. Click any handout then the Download buttons when they appear.
