Camera Raw

What is Camera Raw? - It is not one file format, but many. Camera Raw formats are proprietary, developed by camera manufacturers to best handle the data produced by individual models. Hence, the Raw file format produced by Canon's EOS 5D will differ from that produced by the Nikon D3 and even from other Canon dSLRs.
Though there are some important differences. Raw is just another file format like JPEG or TIFF. The major difference is that Raw files contain unprocessed data from the camera sensor. Before Raw data can be viewed as an RGB image, they have to undergo a number of processes. If you shoot in an RGB format, such as TIFF or JPEG, this processing is done in the camera.