4K resolution is a generic term for display devices or content having horizontal resolution on the order of 4,000 pixels. Several 4K resolutions exist in the fields of digital television and digital cinematography. In the movie projection industry, Digital Cinema Initiatives (DCI) is the dominant 4K standard.
4K has become the common consumer friendly name for UHDTV but technically it is not 4K. Consumer 4K resolution of 3840 x 2160 (at a 16:9, or 1.78:1 aspect ratio) differs from the industry standard of 4096 x 2160 (at a 1.9:1 aspect ratio).