Smart Maintenance and Reliability Engineering (SMRE) in manufacturing leverages advanced technologies such as Industrial Internet of Things (IIoT), Artificial Intelligence (AI), and Machine Learning (ML) to enhance asset performance, reduce downtime, and optimize maintenance strategies. By integrating predictive maintenance, condition monitoring, and real-time data analytics, SMRE improves operational efficiency and extends equipment lifespan. This paper explores the role of digital twins, cloud computing, and cyber-physical systems in revolutionizing maintenance practices. The study also discusses challenges, implementation strategies, and future trends in smart maintenance for sustainable and resilient manufacturing systems.