What does the pH scale measure?

The pH scale specifically measures the acidity or basicity of a solution, providing a numerical representation of the concentration of hydrogen ions (H⁺) present. On this logarithmic scale, a pH value less than 7 indicates an acidic solution, a pH of 7 represents neutrality, and a pH greater than 7 signifies a basic (alkaline) solution. This measure is crucial in chemistry and biology as it influences various chemical reactions and biological processes. For instance, enzymatic activities in biological systems can be highly sensitive to changes in pH, making its measurement vital in many scientific fields.