Television
Today flat panel displays are the usual kind.  These are usually flat rectangles with straight edges.  This long rectangle looks more like the shape of a movie theatre screen.  This is called widescreen.  If a widescreen set was 30 cm tall, it would be 53 cm wide.  For this to work best, TV shows also need to be made in widescreen.  Widescreen sets can still be any size, but they have the same widescreen shape.