From Adobe Systems:
Lightroom makes digital photography easier, faster, and more amazing. Experiment without limits in a nondestructive editing environment. Perfect your shots with advanced controls for tone, contrast, color, and more. Efficiently organize all your photos and share them almost anywhere.
Keywords and collections make it easy to categorize, find, and manage your favorite photos.
Use the Lightroom Develop module to make non-destructive adjustments, such as cropping, color correction, spot removal, tonal adjustments, and exposure.
In Lightroom, you do not save photos in the traditional sense. Instead, you export new sets of files that include Develop module adjustments. Lightroom export supports a variety of file formats suitable for a wide range of uses. For example, you can export photos as JPEGs to share online, or as TIFFs for a print publication.