Thermal mass refers to the ability of a material to absorb, store, and release heat. Materials with high thermal mass, such as concrete, brick, or stone, can help regulate indoor temperatures by absorbing heat during the day and releasing it at night. This property is beneficial in energy-efficient building design, as it can reduce the need for heating and cooling systems. In contrast, materials with low thermal mass, like wood or insulation, do not retain heat as effectively. By strategically using thermal mass in construction, architects can create comfortable living spaces that maintain stable temperatures, ultimately leading to energy savings and improved comfort for occupants.