I recently read a newsgroup thread that started with someone asking just what high definition was. The thread wound in some surprising ways, with individuals asserting, among other things, that anything 16:9 was high definition and that 480i digital content was high definition (while presumably 480i analog was not). I suspect most of you wouldn’t agree. After all, we all know 720p and 1080i are HD while anything less is SD, right? Well things aren’t quite so clear cut.