4K resolution relates to a horizontal display resolution of 4,000 pixels. Digital television and digital cinematography experiments various 4k resolutions. 3840×2160 is a dominant 4K standard and used by media television, while the cinema industry uses 4096×2160.
The term of 4K is comprehensive to any resolution with a horizontal pixel of 4000. Separate different 4K resolutions have been standardized by numerous organisations.
Standardised 4K and Ultra HD are more popular than 2160 pixels. Motion Pictures and other digital camera dealers have exercised 4K photos for photographs and it seems like high resolution even though 3840×2160 pixels similar to the 8.3 megapixels, which can not say high resolution for photographs.

Digital cinema system specification

In 2005, digital cinema initiatives (DCI), released the digital cinema system features. This citing underlay the 2K and 4K format for the cinema industry. Its  resolution is 2048×1080 and 4096×2160 respectively.

2K segmentations can have a frame rate of 24 or 48 fps and 4K segmentations have a frame rate of 24 fps. Following these words exist in the cinema industry with the DCI standard, and they are considered as informal terms for any resolution nearby 2,000 or 4000 pixels in width.

SMPTE UHD TV STANDARD

In 2007, motion picture and television engineers released SMPTE 2036-1, which describe parameters for two UHD TV systems called UHD TV one and UHD TV to install the standard defines the characteristics for the system.

ITU – R  UHD TV standard

In 2012, the international telecommunication Union, Radio Communication sector released the ITU–R BT.2020. It is also known as the Ultra high definition television (UHDTV). It accepts the equal parameters in SMPTE ST 2036-1.

CEA Ultra HD

October 2012, the Consumer Electronics Association advertised their definition of the concept Ultra high definition or Ultra HD for marketing consumer display devices. CEA evaluate an Ultra HD product for TV, monitor or projector with the following features
●     resolution - 3840 × 2160 for larger
●     ratio - 16: 9 or wider
●    processing images according to the colour
●    space defined in ITU–R BT.709
●    Capable of upscaling HD content

2160 pixel resolution

Certain 4K resolutions like 3840×2160 are frequently defined to 2160 pixels. This name goes along with former HDTV and SDTV formats.

Cinema wide 4K

In 2019, Sony was acknowledged as the cinemawide trademark by the European Union Intellectual Property Office (EUIPO). The trademark incorporates electronic devices including smartphones. The standard define a CinemaWide 4K has following highlights:-
●    resolution - 3840×1644 or larger
●    ratio of 21:9
●    capable of playing back 4K resolution video
●    an aspect ratio of 2160 pixel is 21:9

Conclusion

4K resolution is a term that tells about the density of dots or pixels. High resolution images tell about every single pixel quantity on the screen. The "K" in 4K stands for 1000 that means a TV has a horizontal resolution of 4000 pixels. High resolution TVs are durable products and now in trending. If you have a plan for purchasing a new one, then go for a 4K TV.  

What is 4K resolution