Biological assays are laboratory tests used to measure the effects of substances on living organisms or biological systems. They help scientists evaluate the potency, efficacy, and safety of drugs, chemicals, or biological products. Common types of assays include enzyme assays, cell-based assays, and immunoassays, each designed to assess specific biological activities. These tests are crucial in fields like pharmacology, toxicology, and biotechnology. By providing quantitative data, biological assays support the development of new therapies and ensure that existing products meet safety standards. They play a vital role in advancing medical research and improving public health.