Operational research (OR) is a process used to identify and solve health program problems through a continuous cycle of problem identification, strategy selection, strategy testing and evaluation, information dissemination, and utilization. The document discusses how OR has been used to optimize HIV interventions, understand cost-effectiveness, and improve care for vulnerable populations. Some example areas where OR has focused include prevention of mother-to-child transmission, increasing access to antiretroviral therapy, and integrating HIV/AIDS services with other health programs.