From the website: Many serious photographers prefer Raw files (also referred to as RAW) because they allow for the creation of 16-bit images. Since a JPEG file is limited to 8-bit images, raw files preserve more of the color that your camera's sensor can capture. When you shoot Raw, all of the processing that would normally occur inside your camera gets moved into your desktop computer. Because the basic image processing decisions are left up to you, you can often coax much better images from a raw file than you can from a JPEG. Finally, because raw files are uncompressed, they lack the compression artifacts that can occur in a JPEG image.
That's what a RAW file allows you to do. The article continues to an interview with the Aperture product manager, Joe Schorr.
