Joules
The joule (J) is the SI unit of energy, named after the English physicist James Prescott Joule. It is the work done when a force of one newton moves an object by one meter in the direction of the force, so it is sometimes known as a newton-meter. It is also one watt-second.
Therm (US)
A US therm is 105,480,400 joules, which is 100,000 Btu (59°F) and roughly the energy in 100 cubic feet of natural gas. US gas bills are often given in therms.