Used as a pH indicator in acid-base titrations, particularly effective in two pH ranges: 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 processes. Also utilized in microbiology for testing bacterial fermentation and in some culture media to monitor pH shifts during microbial growth. Its dual transition range makes it suitable for detecting both strong acid-strong base and weak acid-strong base reactions.