The SI system of units have been revamped recently.
Instead of being based on 7 base units, it is now based on 7 physical constants. Don’t worry. The magnitude of the 7 base units (kg, m , s, etc) are not affected. It’s only the way they are defined that have been changed.
The seven defining constants are:
- the caesium hyperfine frequency ΔνCs
- the speed of light in vacuum c
- the Planck constant h
- the elementary charge e
- the Boltzmann constant k
- the Avogadro constant NA, and
- the luminous efficacy of a defined visible radiation Kcd
Watch the following video if you’re interested to know the rational for the change.