Data describing the camera settings that is stored with the digital picture file. See HERE for more details.
RAW data is the term usually used to describe data captured by the camera in an unprocessed form. It is usually used where it is intended to use computer processing to "develop" the file to JPEG or TIFF. RAW has the advantage that adjustments can be made in the conversion process (e.g; to the White Balance) that would not be possible if capturing directly in JPEG format. On the down-side, RAW files tend to be large (it uses a lossless compression) and require software to view and convert the files to a working format. RAW is often ldescribed as the equivalent of the film negative, whereas the final JPEG or TIFF file is the equivalent of the print.