Aperture 3 from Apple is a complete photo management and editing suite for Mac OS X Leopard and Snow Leopard. Designed with enthusiasts and professionals in mind, Aperture is built around a nondestructive editing philosophy. Rather than make changes to your original digital images themselves, Aperture leaves them untouched. Any adjustments or edits made are stored on a database and applied to an image on the fly, so that you'll always be able to access your original capture. This allows you to post-process a photograph in as many ways as you'd like, without the danger of making irrevocable changes to your original image.