720
720 is the number of visible lines for High Definition Television(HDTV) at the lower resolution, and 1,080 lines at full resolution. The total number of lines is 750, but since 30 lines are in the vertical blanking interval and not visible, the resulting visible line count is 720.
The 720 standard has 1,280 visible pixels per line, for a total of 1,650 with horizontal blanking. The 720 line count is often specified with the suffix "p" as 720p, which stands for progressive scan. The frame rate is separated by a horizontal bar, as in 720p/25.
In progressive scan, the image builds continuously from top to bottom. Progressive scan knows only one full frame and, in contrast to interlaced scan, also has only one vertical blanking interval.
This is in contrast to the display with interlaced scanning. This display technique is marked with "i", which stands for interlaced, and has two fields. The corresponding display is called 720i.