Some weeks ago, all countries in the world changed the definitions for the following base units of our international system of units (SI system): kilogram, ampere, Kelvin, and mole. This decision means that starting from 20.5.2019 all SI units are defined in terms of constants of nature. Even if nothing has changed in our daily life, some adjustments were needed in the area of high-precision electrical measurements. Above all, the new international system of units will be more stable.
The quantized Hall resistance (Nobel Prize 1985) played a crucial role in the realization of this new SI system, since this quantum resistor can be used not only for high-precision measurements of electrical standards, but also for the realization of an electronic kilogram.