16:9 is a widescreen aspect ratio with a width of 16 units and height of 9 units.

Once seen as an "exotic" aspect ratio, since 2009, it has become the most common aspect ratio for televisions and computer monitors, and is also the universal standard image format for the universal 1080p, 2160p and 4320p formats.

16:9 or "sixteen-nine" is the universal widescreen standard format and Wide-aspect Clear-vision. Japan's Hi-Vision originally started with a 15:9 ratio but converted when the international standards group introduced the wider ratio 16:9. Many digital video cameras have the capability to record in 16:9, and this is the only widescreen aspect ratio natively supported by Blu-ray Disc. It is also the native aspect ratio of the Blu-ray Disc, but Blu-ray Disc producers can also choose to show even a wider ratio such as 2.40:1 within the 16:9 frame adding Letterbox black bars within the image itself.