From a quick survey, when the camera stores as TIFF it is using 8 bits/color. The sensor, (and RAW mode), provides (the equivalent of) 12 bits per color. So, by storing as TIFF you are still throwing away some of the available information. This normally would not matter if everything was exposed correctly when you take the shot. However, if your metering is off, or if the scene has an extreme brightness range, the extra RAW bits can enable finer adjustments in post processing. [In a way, you can think of it as automatically bracketing the exposure.] But, again, normally such bracketing isn't needed, so TIFF works fine. [Folks, of course, will point out other advantages of RAW, but I think this catches it pretty well.] JPEG is a "lossy" compresion technique. So, there are small imperfections in the stored image. For just viewing the "straight" images, or for printing, these imperfections are normally invisible. However, if you do any post processing they cumulatively get worse. Here, by post processing, I mean even simple things like cropping, rotating, resizing, sharpening, adjusting contrast. Still, for most occasions, even with a little post processing you will not see any significant problems. Here is an original, and a SEVERELY tortured jpeg. A moderate amount of postwork on a jpeg really does not cause much of a problem. But the effect is visible, so it is best whenever possible to start with a lossless original, like RAW or TIFF.