Dynamic range in photography describes the ratio between the maximum (white) and minimum (black) measurable light intensities. Good dynamic range can illuminate the details in dark or bright settings to improve the quality of your image.
High dynamic range photos consist of two or more of the same photo taken at different exposures. When both overexposed and underexposed photos are layered on top of each other, they create an image that maintains details in the lightest and darkest areas of the image, far beyond what the camera could produce in a single image.
Review the photos below for examples of dynamic range to get a visual understanding of the limits of your camera and output devices.