What's a BTU and Why is it Important?

BTU – British Thermal Unit

The British Thermal Unit (BTU) is a measure of heat content in fuels or energy sources. It is defined as the amount of heat required to raise the temperature of one pound of liquid water by 1 degree Fahrenheit. BTUs are important because they allow us to compare different energy sources or fuels on an equal basis. By converting the physical units of measure (such as weight or volume) of different fuels into a common unit of measurement, we can compare their energy or heat content. For example, the price of natural gas in the United States is often quoted in dollars per million BTUs.

Source: EIA.gov