Cytotoxicity assays are laboratory tests used to measure the toxicity of substances on cells. These assays help researchers determine how harmful a chemical, drug, or other agent is to living cells, which is crucial in drug development and safety assessments. Common methods include the MTT assay, which assesses cell viability based on metabolic activity, and the LDH assay, which measures cell membrane integrity. These assays are essential in various fields, including pharmaceutical research, toxicology, and cancer research. By understanding cytotoxic effects, scientists can identify potential therapeutic agents and evaluate the safety of new compounds before clinical use.