“Some of you may have heard this term before, some not, but for everyone, it’s a great tip for optimizing the quality of the image coming from your sensor. So to understand how to shoot to the right, first we need to understand the camera’s histogram.
Virtually all DSLRs and many higher-level compacts have what’s known as a histogram display. A histogram is basically a graph showing the distribution of light in your images, from the shadows to the highlights. The left side of the graph represents the darkest shadows in the image whilst the right side represents the brightest highlights. A good exposure is one that keeps all that information within the confines of the graph. If the graph is sliding off the scale to the left, you are losing shadow detail, conversely if it is sliding off to the right you are “blowing” the highlights.” This article by Jason Row on Lightstalking gives a very simple explanation of the use of the histogram. I suggest you read all of the article here

