The term "4K" for televisions and displays sounds like a marketing invention, but it has a genuine technical basis rooted in the film industry rather than consumer electronics. Unlike earlier resolution names such as 480p, 720p and 1080p, which describe vertical pixel count, "4K" refers to a horizontal pixel count of roughly 4,000, a naming convention that has stuck as displays have advanced and is set to continue with the still-distant "8K" standard.

The name originates from the Digital Cinema Initiatives (DCI), a group formed by major studios including MGM, Paramount, Universal and Sony in the early 2000s, whose 2005 standards defined cinema resolutions of 2K (2,048 x 1,080) and 4K (4,096 x 2,160). Home entertainment's version of 4K is actually 3,840 x 2,160 pixels, slightly narrower than the cinema standard, but its name instead reflects that it is exactly four times the pixel count of 1080p. The article also unpicks related terms: "2160p" is the more literal but less catchy equivalent; "Ultra HD" is a general marketing label; and "QHD" or "1440p" (2,560 x 1,440) sits between 1080p and 4K, primarily used in monitors rather than TV or streaming content, since it derives from being four times 720p rather than 1080p.