4K UHD, often just called 4K, refers to a display resolution of 3840 by 2160 pixels. The name comes from the horizontal pixel count being close to four thousand, and Ultra HD, or UHD, is the consumer television standard built around this resolution. It has roughly four times as many pixels as Full HD's 1920 by 1080.
In practice, 4K is now the standard resolution across almost the entire television market, from budget models to the most expensive sets, and the great majority of streaming content, many broadcasts and most current games support it. The extra detail is most visible on larger screens or when sitting relatively close, since at typical sofa distances on a smaller screen the difference from Full HD becomes harder to see.
A 4K resolution also pairs with other features such as HDR and higher refresh rates to improve the overall picture, rather than working in isolation. Our guide to TV size and viewing distance explains how screen size, resolution and seating distance relate to each other.
