pH stands for "potential hydrogen" or "power of hydrogen".

On a simple level, the pH scale can be viewed as a ranking of hydrogen ions in a solution.

- The more hydrogen ions → the lower the pH number → the more acidic the solution.
- We could write the scale using the number of hydrogen ions (eg. 1 x 10
^{-14}, 1 x 10^{-13}, 1 x 10^{-12}, etc.) - However, it would be easier if we use the power: 1 x 10
^{-}^{(power)} - By applying a logarithmic scale, the numbers are simplified to a single digit.
- We put a negative in front of the log to remove the negative power.