Before 4K TVs became ubiquitous, 2K TVs were the most common type of HDTV set with a screen resolution of 1,920 horizontal and 1,080 vertical pixels (1080p). Laptops and computer monitors are also widely available in 2K resolution for movie viewing. Prior to 4K TVs, there was no "2K" designation. The 2K was coined to contrast a regular 2K HDTV from 4K Ultra HD. See 1080p
2K 1920x1080 (see DTV)
4K 3840x2160 (see 4K TV).
4.5K 4480x2520 (see 4.5K resolution).
5K 5120x2880 (see 5K monitor)
6K 6144x3160 (see 6K resolution)
8K 7680x4320 (see 8K TV)