SDTV, also know as Standard Definition Television, is the basic format for digital TV and it provides pictures and sound superior to the finest analog TV. The picture and sound quality are noticeably better because digital transmissions are free of snow, ghosts, and static noises.
The digital picture quality of SDTV at 480i (640 x 480) resolution is sharper than today's analog TVs.
The audio is digital, so sound quality is better than on an analog TV, similar to a CD compared to FM or digital radio.
All TV stations were required by law to convert to digital only TV broadcast; however, they all may not offer High-Definition (HD) broadcast. Most stations offer HD programming.
The Standard Definition TV picture format is the lowest resolution transmitted by terrestrial (over-the-air) TV stations.