Widely used as a color-forming agent in thermal paper coatings, this compound enables image development upon heating, making it essential in receipt papers, labels, and fax papers. It remains colorless at room temperature and turns dark upon exposure to heat, reacting with acidic developers in the paper matrix. Its sharp color change and stability support high-quality printing and long-lasting image retention. Commonly found in point-of-sale systems and ticketing due to reliable performance and cost-effective production.