576i is a standard-definition video mode originally used for terrestrial television in most countries of the world where the utility frequency for electric power distribution is 50 hz. because of its close association with the color encoding system, it is often referred to as simply pal, pal/secam or secam when compared to its 60 hz (typically, see pal-m) ntsc-color-encoded counterpart, 480i. in digital applications it is usually referred to as "576i"; in analogue contexts it is often called "625 lines", and the aspect ratio is usually 4:3 in analogue transmission and 16:9 in digital transmission.