Standard-definition television (SDTV) is a television system that uses a resolution that is not considered to be either high-definition television(HDTV 720p and 1080p) or enhanced-definition television (EDTV 480p). The two common SDTV signal types are 576i, with 576 interlaced lines of resolution, derived from the European-developed PAL and SECAM systems; and 480i based on the American National Television System Committee NTSC system.
Your wikipedia post says that anything above 480 is HD. This wikipedia post says the same. So 480i and 480p are not technically HD.
Edited by Bond 007 - 3/15/13 at 2:29pm