An "organ-on-a-chip" is a small device that mimics the functions of human organs using living cells. These chips are designed to replicate the mechanical and biochemical environments of real organs, allowing researchers to study how diseases develop and how drugs affect the body without using animals. These devices can simulate various organs, such as the heart, liver, or lungs, and are often made from flexible materials. By providing a controlled environment, organ-on-a-chip technology helps scientists understand organ behavior, test new treatments, and improve personalized medicine approaches.