pH is a measure of how acidic or basic a solution is, specifically indicating the concentration of hydrogen ions ($$H^+$$) present in that solution. The pH scale ranges from 0 to 14, where a pH of 7 is considered neutral, values below 7 represent acidic solutions, and values above 7 indicate basic (alkaline) solutions. Understanding pH is crucial for various water treatment and management processes, as it affects chemical reactions, biological activity, and the overall quality of water.