4K is the resolution - 4096x2170 pixels to be exact. It's 4 times the resolution of HDTV. There are 4K projectors starting to come out, but the problem is, there's no 4K content at the moment. The projectors have to upscale the HDTV image to the 4K resolution, and Scott doesn't think that Hollywood will embrace 4K anytime soon for the home market. Streaming will be an issue, too. So, for now, 4K projectors are best for theaters, not the home market.