If you are one of those people who curse at their TV’s when you see a black bar atop and beneath your movie, then High-Def Digest is out to help you understand why it’s the case. As it turns out, it’s not a bug, and if you are seeing a movie with black bars, that’s how it’s supposed to be.
At the dawn of the motion picture era, there was no single standardized aspect ratio for silent films. Depending on the camera used, some were a little wider or a little narrower than others, but all were roughly squarish in appearance. Eventually, a standard emerged, known as Academy Ratio. Films of this type measured at an aspect ratio of 1.37:1, which means that the picture was 1.37 times wider than it was tall.
Source: High-Def Digest