4k resolution HDTV in general refers to a resolution of roughly 4,000 pixels wide and about 2,000 pixels high. That makes it the equivalent of four 1080p screens in height and length. Currently there are no 4k HDTV in production. The one which comes under the name 4k HDTV are really Quad HD which has a resolution of 3840*2160, slightly smaller in length than 4k (4096*2160). 4k TVs are advanced in terms of hardware and not in terms of software. The screen size is bigger but the resolution only depends on the cable provider otherwise it has to stretch the image to fit the screen. Currently YouTube is the only online provider of 4k streaming videos. The 4k HD technology will take a long time to come in normal day life. So better go with some other HDTV as it will take at least a couple of years for cable providers to adapt to new technology. But my suggestion is don’t buy 55" Sony (Sony KDL55BX520) as it got bad reviews and users claim the motions are blurring.