Pillarbox

The pillarbox effect occurs in widescreen video displays when black bars (mattes or masking) are placed on the sides of the image.

Some older arcade games that had a tall vertical and short horizontal are displayed in pillarbox even on 4:3 televisions.

Some high-definition television networks and TV stations use "stylized pillarboxing", meaning they fill-in the blank areas on the sides with their HD logo or other still or motion graphics, when the program being shown is only available in 4:3 aspect ratio (standard definition).

This also tells widescreen television sets with automatic resizing not to stretch the video, and instead to present it in the proper aspect ratio (although conversely, this may cause fullscreen SDTV sets and analog cable TV headends to horizontally compress or to windowbox the video).

Some channels have a similar format called "enhanced HD", in which extra informative graphics and text is shown on the side, such as expanded stock quotes, charts, and graphs on CNBC HD+ in the past.