Joule

The joule is defined as:

$1\text{ J} = 1\text{ N} \times 1\text{ m} = 1\text{ kg m}^2\text{/s}^2$

It is also the energy transferred when 1 W of power operates for 1 s, or when 1 A of current flows through a potential difference of 1 V for 1 s.

Common multiples: 1 kJ = 1000 J; 1 MJ = $10^6$ J.