HDTV has the most lines on screen

High-definition television, HDTV, provides the highest-quality picture and sound currently available. The resolution approaches the quality of 35mm movies and CD sound.

Standard definition television, a digital alternative comparable to the quality of a DVD, has 525 scanning lines compared to 1,125 for HDTV. Analog sets have only 400 lines.

HDTV sets have a more rectangular screen than conventional analog sets. The shape is closer to the screens at movie theaters. HDTV's picture is referred to as a 16:9 aspect ratio, compared to the 4:3 aspect ratio of standard TV.

HDTV programming can be viewed on conventional TV screen in letterbox format with black areas above and below the picture.

Analog programming can be viewed on HDTVs with the picture centered or "stretched" to fill the screen.