To manage the imbalance between energy supply and demand in various energy systems such as energy storage and energy conversion, “phase change materials” are presented as promising options for these applications. To overcome the long-standing disadvantages of PCMs, for instance, small values of thermal conductivity, liquid leakage, separation of phase, and the problem of supercooling, advanced phase change composites (PCCs) manufactured by chemical modifications or the incorporation of functional additives are essential to overcome these disadvantages and promote the large-scale application of PCMs. Herein, we discuss a complete assessment of the recent development and crucial topics concerning PCCs, with a brief description of PCC preparation using different techniques, enhancing PCCs thermal conductivity approaches, and their applications. The various techniques of elaboration of PCCs used can be illustrated as polymerization, encapsulation, and hybrid confinement. Phase change materials (PCCs) are described as potential energy materials for thermal management and storage of thermal energy with the intention of fulfilling the gap between the source of energy and the need in different energy systems. Herein, we give a global presentation of PCCs subjects including PCC elaboration, enhancing thermal conductivity techniques, and applications.