1080i, 720p...what is this ?

The older TV sets, that we grew up watching were called stadard definition—480 lines of picture stacked on top of one another to make up the picture. Pretty sore quality campared with today's standards. The TV refreshed itself 30 times per second (30 FPS, frames per second), it lacked the horsepower to process the full image on each scan. So it just drew every other line, and updated the remaining lines on the next refresh. The images flitted so fast that your brain stihed the two sets of lines together. It is called interlacing, and the screens display properties would be called 480i, i for interlaced.

HD boosts 720 lines or more that can update every line in every refresh pass, progressive scan. The latest TVs can display 1080p. 1080p sources right now are limited to blue-ray and HD DVD players, as well as a few video games..and cable services top out at either 720p or 1080i.

When the action speeds up, things get a bit trickier, TVs use complex algorithims to account for faster moving objects that change positions between frames, guessing which part of the image has changed. A wrong guess leads to visual artifacts and ghosting.

Those are the basics, of HD for consumers out there right now.