With most digital cameras there is the ability to store photos in "RAW" format instead of the standard JPG/JPEG.

When you take shots to be stored in RAW, the first thing you notice is that it takes a really long time for the cam to finish storing the photo after taking the shot.

The second thing you notice is that it’s not the easiest thing in the world to work with if you don’t have the proper software to read the RAW format.

The third thing you notice is that it takes seemingly forever to get RAW format imagery off the camera because it’s just so honkin’ huge in file size.

Is there any particular advantage to using RAW?

Yes and no. More on that in a moment.

What does RAW mean?

RAW is a "minimally processed" digital image stored on your digital camera when the shot is taken. You can think of them as "unprocessed" photos.

Is RAW the same on all digital cameras?

NO. This is because digital cameras of different makes have different ways of producing an unprocessed image.

Yes, this is confusing but it’s the truth. When you take a photo "in RAW", the actual data of the image is different per make. Canon is different from Pentax is different from Casio is different from Nikon is different from Olympus, etc. You get the idea. RAW is not a universal format.

How do I work with a RAW image?

Typically you need the software that came provided with your digital camera to work with them at all.

Granted, Picasa does support many RAW formats from different manufacturers, however its editing capabilities are very limited. Better to use the software that came with the camera.

What is the reason I would want a RAW image?

Best possible quality and most editing capability. The RAW file gives you more control over the final image - particularly for print purposes.

When would be a bad time to use RAW?

When shooting/storing in RAW it takes the camera a long time to save the file because each one is humongous. If you’re doing fast-style photography, RAW is a bad idea.

When would be a good time to use RAW?

Portraits, i.e. shots where you can take your time, RAW may serve a good advantage to you.

If you want to learn more about the technical stuff concerning RAW, see the Wikipedia article at http://en.wikipedia.org/wiki/Raw_image_format