Cytotoxicity refers to the capacity of a substance or agent to damage or kill living cells, reflecting a critical parameter in pharmacology, toxicology, and biomedicine. It is distinct from cytostatic effects, which inhibit cell growth and proliferation without causing cell death. Cytotoxic agents can induce a range of cellular responses, including inhibition of cell growth, induction of apoptotic or necrotic cell death, and disruption of metabolic or structural cellular integrity. Assessing cytotoxicity is fundamental for evaluating the safety and efficacy of pharmaceutical compounds, chemicals, and biomaterials, as it helps predict potential adverse effects and guides therapeutic development.