BT.2020 is also called s Rec. 2020. It is a set of specifications covering various aspects of video broadcasting.

On August 23, 2012, the International Telecommunications Union (ITU) released its first version of Rec. 2020, defining various aspects of ultra-high-definition television (UHDTV) with standard dynamic range (SDR) and wide color gamut (WCG).

BT.2020 has clear regulations and requirements in terms of picture resolutions, frame rates, bit depths, digital representation, system colorimetry, transfer characteristics, RGB and luma-chroma color representations, and color arrangement.

Resolution (Square Pixels Only)4K: 3840×2160
8K: 7680×4320
Frame Rate (Progressive Scan Only)  120p, 119.88p, 100p, 60p, 59.94p, 50p,
30p, 29.97p, 25p, 24p, or 23.976p
Bit Depth10 or 12 bits per sample

In terms of resolution, BT.2020 defines that 4K should be 3840×2160 and 8K should be 7680×4320. The aspect ratio should be 16:9 and only use square pixels.

System colorimetry requirements are as follows.

Credit:BenQ

To conclude, BT.2020 (Rec. 2020) is a set of specifications defined by ITU to regulate Ultra HD broadcasting industry.