The MTT assay is a colorimetric technique used to assess cell viability and proliferation. It involves the reduction of the yellow MTT dye to purple formazan crystals by metabolically active cells. The intensity of the purple color, measured using a spectrophotometer, correlates with the number of viable cells. This assay is widely used in pharmacology and cancer research to evaluate the effects of drugs on cell growth. It is favored for its simplicity, sensitivity, and ability to provide quantitative results, making it a valuable tool in both basic and applied biological research.