4K is a catchier marketing term than 2160p, but the resolution also has this name for a reason. Screen resolutions are one of the many tech terms that go by various names, making it difficult to distinguish them. You might hear 720p, Full HD, and 4K all in the same conversation, for instance.

Since 4K doesn't follow the pattern set by 480p, 720p, and 1080p, it might seem like it's just a marketing term. Even though it's technically not 100 percent accurate, 4K is an applicable way of describing these displays. The name has roots outside of consumer displays while still mapping to the video formats and screens we're familiar with.

4K was first used not to refer to TVs, but instead to digital film used in movie theaters. In the early 2000s, several big movie studios like MGM, Paramount, Universal, and Sony formed a group called Digital Cinema Initiatives (DCI) to define standards for digital movies. The first edition, published in 2005, included two resolutions: 2K (2,048 x 1,080 pixels) and 4K (4,096 x 2,160 pixels).

The '4K' name used for consumer tech has a different connection: It's exactly four times the size of 1080p's 1,920 x 1,080 pixels. Its horizontal and vertical pixel counts are each twice that of 1080p. Another term for 4K is 2160p, which continues the tradition of using a resolution's vertical pixel count for its name. While accurate, this isn't used as often since '4K' is a lot catchier and easier to use in marketing.