What does pH measure?

pH is a scale that measures the acidity or basicity of a solution, specifically quantifying the concentration of hydrogen ions (H⁺) present. A low pH value (typically below 7) indicates an acidic solution, where there is a higher concentration of hydrogen ions, while a high pH value (above 7) indicates a basic or alkaline solution, where there is a lower concentration of hydrogen ions. A pH of 7 is considered neutral, which is typical for pure water.

This understanding of pH is essential in various fields, including chemistry, biology, and environmental science, as it helps in understanding the behavior of substances in a solution, their reactivity, and their potential effects biologically and chemically.