Short answers, pulled from the story.
A joule is the unit of energy in the International System of Units, with the symbol J. In SI base units, one joule equals one kilogram-metre squared per second squared. It is the work done when a force of one newton moves a body one metre in the direction of the force.
The joule is named after the English physicist James Prescott Joule, who lived from 1818 to 1889. Wilhelm Siemens proposed the name in 1882, citing Joule's work developing the dynamical theory of heat. Joule was 63 and retired at the time of the proposal.
The joule was officially adopted on the 31st of August 1889, at the second International Electrical Congress, alongside the watt and the quadrant. The definition J = kg m2 s-2 was set in 1946 and declared in the modern International System of Units in 1960.
One joule equals the work of producing one watt of power for one second, known as the watt-second, a relationship used to define the watt. One joule also equals the work of moving one coulomb of charge through a potential difference of one volt, which can be used to define the volt.
The joule measures energy, a scalar formed from the dot product of force and displacement, while the newton-metre measures torque, a vector formed from the cross product of force and distance. The General Conference on Weights and Measures gave a special name only to energy, leaving torque as the plain newton-metre to avoid confusion.
One joule is about the energy to lift an apple of 101.97 grams up one metre, and the heat a resting person releases every sixtieth of a second. On larger scales, the bomb called Little Boy released about 63 terajoules, and the Sun's thermal output is roughly 400 yottajoule-scale units per second.