To fit modern TVs, vertical black bars or 'pillarboxing' is used.

TV shows used to be made using a 4:3 aspect ratio, which is a lot more square than current TVs (this is why 16:9 is often called a widescreen aspect ratio). These horizontal bars are called 'letterboxes.' 21:9 is much wider, so parts of the screen need to be filled with black bars above and below the image in order to fit most TVs. All TVs sold today have an aspect ratio of 16:9, which means that if the width is divided into 16 equal parts, the height of the TV or picture should be 9 parts.ġ6:9 works great for TVs, since that is the aspect ratio used by the majority of today's TV shows, but unfortunately, most movies are made using the cinema standard, which is 21:9. It defines its overall shape, and it is usually presented as W:H (where W is the width, and H is the height). The aspect ratio is the ratio between the width and the height of a display.