Phase Change Materials (PCMs) are promising candidates for thermal energy storage due to their ability to absorb and release heat during phase transitions. Their high energy density and thermal stability make them suitable for applications in buildings, solar systems, and industrial processes. This review provides a structured overview of PCM characterization techniques and performance enhancement strategies. Key methods-such as Differential Scanning Calorimetry (DSC) and the T-history method-are compared in terms of accuracy, representativeness, and practical relevance. Enhancement approaches, including nanoparticle doping, encapsulation, and composite formation, are critically evaluated with respect to thermal conductivity, stability, and cost. Comparative tables and schematic illustrations synthesize findings from recent studies and highlight methodological gaps. Particular emphasis is placed on long-term reliability, material compatibility, and deployment challenges under real operating conditions. The review concludes with perspectives on future research, highlighting hybrid PCM systems and application-specific integration strategies, especially for arid climates and emerging energy infrastructures. This work aims to support researchers and engineers in the selection and optimization of PCMs for sustainable thermal energy storage applications.