Kelvin
The Kelvin is a measurement of absolute temperature. The Kelvin scale is set at zero where it is equivalent to -273.15 degrees Celsius (known as Absolute Zero). The Kelvin scale is able to measure the temperature of the hottest objects in the universe, stars. Kelvins are usually designated with a capital K – so we say 5,000K meaning five thousand Kelvins.
The Kelvin scale is used in the measure of colour temperature. In photography the Kelvin and colour temperature is used in a variety of ways. For example, colour temperature lights can be set as ‘daylight balanced’. A ‘daylight balanced’ light will radiate light that matches a colour temperature determined as daylight (5,600K). Post production image editing can use the Kelvin scale for setting colour matches and processing specific colour factors.
The Kelvin is named after Lord Kelvin 
the Mathematical Physicist and engineer (26 June 1824 – 17 December 1907).