What are the thick black bars that border some of the programs I tune into?
Windowpane Screens: When you view 4:3 (SD) content on a 16:9 HDTV display, you may get an onscreen image with vertical black or gray band on each side of the image. This is called a windowpane screen.
Letterbox Screens: When 16:9 (HD) content is viewed on a 4:3 display, you may see a long and narrow image with the black or gray bands above and below. This is called a letterbox screen.