The pH scale measures the acidity or alkalinity of a solution, ranging from 0 to 14, with 7 being neutral. It is based on the concentration of hydrogen ions (H+) in a solution, where lower values indicate higher acidity and higher values indicate higher alkalinity. The scale is logarithmic, meaning each whole number change represents a tenfold change in acidity or alkalinity. Understanding the pH scale is crucial for various scientific fields, including chemistry, biology, and environmental science. For a detailed explanation, the Wikipedia article on pH is recommended as a comprehensive resource.