RAW data is named NEF data by Nikon.
RAW data can be stored on the memory card, or it can be further processed to get a viewable JPEG or TIFF
Main advantage of RAW data: many of the shooting parameters can be changed after exposure. You can’t change the exposure (obviously) and you can’t change the ISO, but you can change many other parameters.
The second advantage of RAW file is that you can also perform the conversion to an 8-bit or 16-bit TIFF file. TIFF files are larger than JPEG files, but they retain the full quality of the image. second advantage of shooting a RAW file is that you can also perform the conversion to an 8-bit or 16-bit TIFF file.
Details:
TIFF means data is stored as an 8 or 16-bit
RAW means data from most high end digital camera is stored on 12 bit data => there can be 4096 different intensity levels for each pixel.
In an 8-bit file (such as a JPEG), each pixel can have one of 256 different intensity levels.
All printing is done at the 8 bit level
Reason to having 12 bit data: it allows you to perform manipulation to the image without degrading the quality. You can adjust curves and levels to a greater extent, then convert back to 8-bit data for printing. If you want to access all 12 bits of the original RAW file, you can convert to a 16-bit TIFF file.
Notes:
TIFF file is larger than JPEG files but they retain the full quality of the image. They can be compressed or uncompressed. The compression scheme is lossless, meaning that although the file gets a little smaller, no information is lost.
Main reason to shoot JPEG is that you get more shots on a memory card.
RAW means you expect to have to do post exposure processing. If you’re not sure about exposure or white balance, or if you want to maintain the maximum possible allowable post exposure processing, then you’ll want to shoot RAW files, convert to 16-bit TIFF, do all your processing, then convert to 8-bit files for printing.