pH is a quantitative measure of the acidity of a solution . pH is represented on a logarithmic scale from zero to fourteen. A solution is considered acidic if its pH is lower than seven and basic if greater.

For example,Water has a ph of 7.

More specifically, pH is a measure of the concentration of Hydrogen ions in solution. It is given by the negative of the logarithm of the Hydrogen ion concentration in moles per litre to base 10.