Phase Change Materials (PCMs) are substances that absorb or release thermal energy during phase transitions, such as melting or freezing. They can store heat when they change from solid to liquid and release it when they solidify. This property makes them useful for temperature regulation in various applications, including building materials and thermal energy storage systems. PCMs are commonly used in building design to improve energy efficiency. By incorporating these materials, structures can maintain comfortable indoor temperatures, reducing the need for heating and cooling. This not only saves energy but also contributes to sustainability efforts in architecture and construction.