# Question #f25e6

Jul 6, 2017

The SI unit of measurement is the meter (symbol $\text{m}$)

#### Explanation:

By fundamental I'll assume you mean something along the lines of "most used" or "most basic" or "most common".

Essentially the answer to all three of these is the meter ($\text{m}$), which is one of the base SI units of measurement.

The meter is defined as the distance light travels in vacuum in a time period of $\frac{1}{299 , 792 , 458}$ $\text{second}$.

This value comes from the speed of light in vacuum, defined precisely as $299 , 792 , 458$ $\text{m/s}$.