The Adobe Photoshop Lightroom 4 Software Upgrade for Mac and Windows is a complete photo management and editing suite for Mac OS X and Windows. Ideal for enthusiasts and professionals alike, Lightroom takes a nondestructive approach to photo editing, leaving the original files unmolested. All your adjustments and edits are stored in a database and applied to an image on the fly, so that you'll always be able to go back to the original image. This enables you to execute as many post-processing adjustments on a photo as you'd like, without making permanent changes to the original image. Lightroom also serves as a powerful organizational tool for your photographs. Organize photos to suit your needs via an intuitive folder-based data structure. Lightroom lets you store images on multiple storage devices and it stores low-resolution previews of each image in its central database, allowing you to browse photos even when the original files are offline.