The tetrazolium test is a laboratory method used to assess cell viability and metabolic activity. It involves the use of tetrazolium salts, which are colorless compounds that can be reduced by living cells to form a colored formazan product. This color change indicates the presence of viable cells, making it a useful tool in various biological and medical research applications. This test is commonly employed in studies involving plant tissue, microbial cultures, and cancer research. By measuring the intensity of the color produced, researchers can quantify the number of living cells and evaluate the effects of treatments or environmental conditions on cell health.