Used as a pH indicator in acid-base titrations, particularly effective in the pH range of 1.2–2.8 (red to yellow) and 8.0–9.6 (yellow to blue). Commonly applied in educational labs for demonstrating pH changes and in analytical chemistry to determine endpoint in titration reactions. Also utilized in environmental testing to assess the acidity or alkalinity of water samples. Its dual transition range makes it suitable for detecting both strong acid-strong base and weak acid-strong base reactions.