720p (1280×720 px; also called HD Ready or standard HD) is a progressive HDTV signal format with 720 horizontal lines and an aspect ratio (AR) of 16:9 , normally known as widescreen HDTV (1.78:1). All major HDTV broadcasting standards (such as SMPTE 292M) include a 720p format which has a resolution of 1280×720; however, there are other formats, including HDV Playback and AVCHD for camcorders, which use 720p images with the standard HDTV resolution. The frame rate is standards-dependent, and for conventional broadcasting appears in 50 progressive frames per second in former PAL/SECAM countries ( Europe , Australia , others), and 59.94 frames per second in former NTSC countries (North America , Japan , Brazil , others).
The number 720 stands for the 720 horizontal scan lines of imagedisplay resolution (also known as 720 pixels of vertical resolution). The p stands for progressive scan, i.e. non-interlaced. When broadcast at 60.00 frames/s frames per second , 720p features the highest temporal resolution possible under the ATSC and DVB standards. The term assumes a widescreen aspect ratio of 16:9 , thus implying a resolution of 1280×720 px (0.9 megapixels).
720i (720 lines interlaced) is an erroneous term found in numerous sources and publications. Typically, it is a typographical error in which the author is referring to the 720p HDTV format.