Used as a pH indicator in laboratory and industrial applications, particularly in titrations and microbiology. It changes color in the acidic pH range, typically from red at pH 4.4 and below to yellow above pH 6.2. Commonly employed in bacterial identification tests, such as the methyl red test, to detect mixed acid fermentation in enteric bacteria. Also utilized in analytical chemistry for acid-base titrations where a sharp color change in the low pH range is required. Its hydrochloride form improves solubility and stability in aqueous solutions, making it suitable for standardized test preparations.