D65
D65 is standardized viewing condition with 6500 K color temperature. It is the default setting for most monitors and is mainly used in color matching etc. for websites, so in media that are considered primarily to be viewed on the monitor.
In the printing industry, the standard light is D50 according to ISO 3664: 2009 standard, a warmer light than D65 with 5000 Kelvin color temperature, which is also used for color matching on the press and in the evaluation of proofs.