Evaluating the Tonal Range
Dynamic range in music is the range between the faintest and loudest sounds that can be reproduced without distortion. In photography the dynamic range, called the tonal range or contrast, indicates the range of brightness in an image between pure white and pure black.

There are two ways to evaluate the tonal range of an image visually and using a histogram

Visually, images that use the full tonal range look rich and crisp, with vibrant colors and smooth transitions in tones. Those that don't use the full range lack contrast, often looking flat and dull. Details may be missing in highlight and shadow areas or the image may be too dark or light. In these cases you may want to adjust or expand the image's tonal range.