Understanding Photography Histograms
Once you take a photo the camera produces a histogram. This is a key tool for professionals but is too often ignored by beginners because it looks frighteningly complicated.
Reading a histogram
Histograms tell you lots and lots about the photo you just shot.
Firstly, if the levels are bunched to the left, this is a dark shot (but you can see that for yourself by looking at the photo). Equally, if the lines are all to the right of the histogram, it is a light (or 'overexposed' shot).
Although you can see on the photo whether it is dark or light, you cannot usually tell if the highlights are totally blown or the darks have lost all detail. The histogram tells you this, and that is just the beginiing.
Some cameras 'simplify' the histograms so they don't seperate colours. However, unless you are taking monochrome pics, the rgb (colour) histogram is what you need.
Get used to checking the histogram on your digital camera's LCD after each shot. It might seem cumbersome at first, but it really will help you improve your shots.
In general a bell shaped histogram will produce images that have a wide dynamic range without blown highlights or underexposed shadows.