Thymol blue is widely used as a pH indicator in various laboratory and industrial applications. In chemistry labs, it helps determine the acidity or alkalinity of solutions, transitioning from red to yellow in acidic conditions (pH 1.2–2.8) and from yellow to blue in alkaline conditions (pH 8.0–9.6). This makes it particularly useful in titrations to identify the endpoint of reactions. In microbiology, it is employed in culture media to monitor pH changes during microbial growth. Additionally, thymol blue is used in water treatment processes to assess water quality and in the pharmaceutical industry to ensure the stability of formulations. Its versatility and clear color transitions make it a reliable tool for pH monitoring across diverse fields.