Gene delivery is the process by which exogenous genetic material, such as DNA or RNA, is introduced into host cells or tissues. This fundamental concept and set of methodologies in molecular biology, genetics, and biotechnology investigates the development and application of diverse strategies, including viral vectors, non-viral carriers, and physical methods, to efficiently, specifically, and safely transfer genetic information across biological barriers. Its significance lies in its essential role as a research tool for studying gene function and regulation and, critically, as the foundational basis for gene therapy aimed at treating a wide array of genetic and acquired diseases.