Aspect ratio
The aspect ratio of a still image or motion picture describes the proportional relationship between its width and height. Aspect ratio is commonly expressed as two numbers separated by a colon.
Image source
Wikimedia Commons contributors, "File:Filmaspectratios svg.svg," Wikimedia Commons, the free media repository,https://commons.wikimedia.org/w/index.php?title=File:Filmaspectratios_svg.svg&oldid=227494438 (accessed December 5, 2017).
