Grinnell Point in Glacier National Park
Photography is painting with light, we take light through a lens and let it fall across a medium to record it, whether it be film, a CCD, or CMOS. The challenge of photography is that there is a issue of sensitivity to light and dynamic range. Each of these capture media have range of light that they will capture, and that range can be adjusted either by changing film speed or changing the settings of your camera's sensitivity. Generally, the higher the sensitivity, the greater visible grain (film) or noise (digital). In digital photography, that noise is amplified when you try to pull details out by making adjustments to the photo to extend the dynamic range in a photo. Ideally, you make a perfect exposure every time, but life doesn't work that way. The other two options are to fix it in software, or to move high dynamic range techniques (HDR). HDR takes multiples of photos is exact,or at least close, registration and overlays them and in software you choose which layer to reveal to give you a broader range of exposures to work with.
In this case, I was trying to boost the exposure in ways that minimized blowing out the highlights, while pulling detail out of the dark. You can see the amplified noise on the dark side of the mountain. Part of that might be further amplified by the processing that Flickr does in rendering versions of the image that is uploaded. I don't have the aligned multiples, I wish I did as these were great conditions for HDR. Looking at this makes want to go back to the original and reprocess it.