Downloading Microsoft camera codec pack (16.0.0652.0621) will enable your Windows 7 or Vista OS to show RAW format pictures in Windows Explorer and Photo Gallery and it has support for about 120 DSLR cameras. This means that you will no longer get the "unknown file" icon when looking into an album of RAW format images.
The RAW photo format is like a digital negative of a photo made with a DSLR camera. It contains uncompressed data from each individual pixel of the camera sensor and in layman terms its a bigger, unprocessed version of the JPEG photo.
Its not like addons such as the FastPictureViewer Codec Pack did not enable native RAW file support before but its more comfortable to have an in-built solution straight from Windows. Microsoft has even added runabout editing features through Windows. If you want to edit a RAW photo you select the option and Windows automatically creates an editable copy of your RAW file for you to manipulate. The original is safe and you have an already edited JPEG or JPEG-XR file.
Demo Below!
