Starch indicator is widely used in analytical chemistry, particularly in iodometric titrations, to detect the endpoint of reactions involving iodine. When iodine is present in a solution, it forms a deep blue-black complex with starch, providing a clear visual indication of the reaction's completion. This property makes it invaluable in determining the concentration of oxidizing or reducing agents in various samples. For example, it is commonly employed in the titration of vitamin C (ascorbic acid) to measure its concentration in food and pharmaceutical products. Additionally, it is used in water quality testing to assess the levels of residual chlorine or other oxidizing agents. The starch indicator is preferred due to its high sensitivity and the distinct color change, which ensures accurate and reliable results in quantitative analysis.