A BTU, or British Thermal Unit, is a unit of measurement used to quantify heat energy. Specifically, it represents the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit. BTUs are commonly used in heating and cooling systems, such as furnaces and air conditioners, to indicate their energy output or efficiency. In practical terms, understanding BTUs helps consumers choose the right appliances for their homes. For example, a gas stove may have a BTU rating that indicates how much heat it can produce, allowing users to select a model that meets their cooking needs effectively.