Phase Change Materials: The Silent Architects of Thermal Control provides an in-depth examination of the pivotal role phase change materials (PCMs) play in advancing thermal energy storage and enabling more sustainable, efficient energy systems. As the demand for cleaner, smarter and efficient energy solutions grows, this reference bridges the gap between foundational PCM science and the latest innovations, including AI-driven design and diverse real-world applications. The book systematically covers PCM fundamentals such as thermodynamics, molecular design, and structure-property relationships, while also addressing the selection, classification, and performance enhancement of advanced materials like nano-enhanced, bio-based, and composite PCMs. Comprehensive in scope, the book explores practical aspects of PCM integration, including encapsulation techniques, temperature-adaptive materials, and system-level applications across sectors such as solar thermal energy, electronics cooling, building construction, food and pharmaceutical preservation, smart textiles, and biomedical devices. Special emphasis is placed on computational modeling, AI-based optimization, and sustainability, ensuring a well-rounded perspective for both theory and practice. By combining foundational knowledge with current advances and practical case studies, this resource equips researchers, engineers, and advanced students with the tools needed to develop innovative, efficient, and sustainable thermal management solutions across a range of industries. Introduces the application of artificial intelligence and machine learning techniques to predict thermal properties, optimize phase change material (PCM) formulations, and expedite material discovery Explores advanced and emerging industrial applications such as waste heat recovery, solar thermal energy storage, electronic device cooling, and smart infrastructure with real-world case studies Explains molecular and thermodynamic principles governing PCMs behavior, including phase transition mechanisms, structure-property relationships, entropy-enthalpy dynamics, and bonding interactions Integrates sustainability and environmental considerations in thermal energy storage