Aspect ratio refers to the relationship between an image's width and height. Common movie aspect ratios include 1.33:1, 1.85:1, and 2.35:1. Black bars appear on the top and bottom of images when the aspect ratio of the content does not match the viewing device. To deal with this, film studios distribute movies on DVD in both widescreen format, which preserves the original aspect ratio with black bars, and full screen format, which modifies the image to fit a standard screen size.