R-value is a measure of thermal resistance used in the building and construction industry. It indicates how well a material can insulate against heat flow; the higher the R-value, the better the material's insulating effectiveness. R-values are commonly associated with insulation materials, such as fiberglass, foam, and cellulose, which are used in walls, attics, and floors. When selecting insulation for a home or building, understanding R-value is crucial for energy efficiency. Different climates and building designs may require varying R-values to maintain comfortable indoor temperatures. Proper insulation can lead to reduced energy costs and improved comfort levels in living spaces.