Cell viability refers to the health and functionality of a cell. It is a crucial aspect of cellular biology research, as it determines whether a cell is alive, healthy, and capable of performing its normal functions. Cell viability assays are commonly used in research to assess the effects of various treatments, drugs, and environmental factors on cells. By measuring cell viability, researchers can determine the toxicity of substances, evaluate the effectiveness of potential therapies, and study the underlying mechanisms of diseases. Various methods and techniques, such as dye exclusion assays, ATP assays, and flow cytometry, are used to assess cell viability in laboratory settings.