This lecture provides an overview of Implementation Research (IR), focusing on key concepts such as defining implementation problems, designing strategies, and testing them. It covers the importance of IR for infectious diseases, key characteristics, and outcomes. The lecture also discusses the settings and context for identifying IR needs, different types of implementation strategies, and examples of research questions. The instructors summarize the modules, emphasizing the distinction between intervention efficacy and implementation effectiveness, and discussing outcomes like acceptability, adoption, and sustainability.