4:3

4:3 (1.3:1) (generally read as "Four-Three", "Four-by-Three", or "Four-to-Three") for standard television has been in use since the invention of moving picture cameras and many computer monitors used to employ the same aspect ratio. 4:3 was the aspect ratio used for 35 mm films in the silent era. It is also very close to the 1.375:1 Academy ratio, defined by the Academy of Motion Picture Arts and Sciences as a standard after the advent of optical sound-on-film. By having TV match this aspect ratio, movies originally photographed on 35 mm film could be satisfactorily viewed on TV in the early days of the medium (i.e. the 1940s and the 1950s). Since the start of the 21st century broadcasters worldwide are phasing out the 4:3 standard entirely, as manufacturers started to favor the 16:9 aspect ratio of all modern high-definition television sets and broadcast cameras.