Phase-change materials (PCMs) can be used for thermal energy storage. PCMs absorb and release large amounts of energy as they change phase from solid to liquid and back. This latent heat storage allows PCMs to store more energy per unit volume compared to sensible heat storage methods. Effective PCMs for thermal energy storage applications should have suitable melting temperatures, heat of fusion, thermal and mechanical stability over repeated phase changes, and acceptable costs. However, challenges remain regarding material compatibility, conditioning, safety, and cost-effectiveness compared to other thermal energy storage options.