pH, in chemistry, is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions.
pH is a scale of acidity from 0 to 14. It tells how acidic or alkaline a substance is. More acidic solutions have lower pH. More alkaline solutions have higher pH. Substances that aren’t acidic or alkaline (that is, neutral solutions) usually have a pH of 7.
There is a level of acidity or alkalinity, measured by pH, in a substance at any given time. And there’s an acidic/alkaline balance that has to exist for certain metabolic processes to take place, especially in our own bodies.