What does pH primarily measure in a solution?

pH primarily measures the concentration of hydrogen ions in a solution. It is a logarithmic scale that quantifies how acidic or basic a solution is based on the concentration of H⁺ ions. A lower pH value indicates a higher concentration of hydrogen ions, which corresponds to increased acidity, while a higher pH value suggests a lower concentration of hydrogen ions, indicating a more basic solution.

This relationship is crucial in a variety of chemical, biological, and environmental processes, as pH can influence chemical reactions, the availability of nutrients, and the overall health of ecosystems. Understanding pH is essential in fields like agriculture, where soil pH can affect plant growth, or in aquaculture, where water pH can impact fish health.