Some helpful links:
Shot in Raw files/Process Raw files
Camera raw file formats contain unprocessed data from a digital camera’s sensor. Most camera manufacturers save image data in a proprietary camera format. Lightroom reads the data from most cameras and processes it into a full color photo. You use the controls in the Develop module to process and interpret the raw image data for your photo.
DNG files
The Digital Negative (DNG) is a publicly available archival format for raw files generated by digital cameras. By addressing the lack of an open standard for the raw files created by individual camera models, DNG helps ensure that photographers will be able to access their files in the future. You can convert proprietary raw files to DNG from within Lightroom.
Jpeg Files
Joint Photographic Experts Group (JPEG) format is commonly used to display photographs and other continuous-tone images in web photo galleries, slideshows, presentations, and other online services. JPEG retains all color information in an RGB image but compresses file size by selectively discarding data. A JPEG image is automatically decompressed when opened. In most cases, the Best Quality setting produces a result indistinguishable from the original.
TIFF format (Tagged-Image File Format)
(TIFF, TIF) is used to exchange files between applications and computer platforms. TIFF is a flexible bitmap image format supported by virtually all paint, image-editing, and page-layout applications. Also, virtually all desktop scanners can produce TIFF images. Lightroom supports large documents saved in TIFF format (up to 100 million pixels with pixel dimensions of no more than 10,000 on a side). However, most other applications, including older versions of Photoshop (pre-Photoshop CS), do not support documents with file sizes greater than 2 GB.The TIFF format provides greater compression and industry compatibility than Photoshop format (PSD), and is the recommended format for exchanging files between Lightroom and Photoshop. In Lightroom, you can export TIFF image files with a bit depth of 8 bits or 16 bits per channel.
