R-134a, also known as tetrafluoroethane, is a colorless gas commonly used as a refrigerant in air conditioning systems and refrigeration units. It is favored for its low toxicity and ozone depletion potential, making it a more environmentally friendly alternative to older refrigerants like R-12. R-134a operates effectively in a variety of temperatures and pressures, allowing it to efficiently transfer heat. It is widely used in automotive air conditioning, commercial refrigeration, and household appliances, contributing to the cooling processes in many everyday devices.