This is a resolution which delivers 1080 lines of picture progressively (in other words: simultaneously) on the screen. Effectively this is 2 million pixels, 60 times per second and thus by far the greatest development in commercial picture to date. This format is recognised as "true HD" and is available from BluRay disc and net-based downloads. Nevertheless, this is set to become the standard over the next few years as other, even higher resolution, formats are developed.
One very big advantage to HD screens is the fact that screen size can increase in relatively small rooms. A screen size of between 3-5 times the width of the base of the TV is required for good visual comfort. With standard resolution screens, it was preferable to be slightly further from the screen, or smaller screen size as the ideal, as this lessened the effect of the low resolution and reduced viewer fatigue. Because HD screens have more detail, one can be closer to them, or increase the screen size and have a more cinematic experience in a normal sized room.