measures acidity or alkalinity of a substance on a scale
pH is a measure of how acidic or basic a substance is, on a scale from 0 to 14. A pH of 7 is considered neutral, while values below 7 indicate acidity and values above 7 indicate alkalinity. In the context of hair and scalp health, maintaining a balanced pH (around 4.5 to 5.5) is crucial for preventing issues like dryness, irritation, and microbial growth.