In 2004, Bhargava introduced a new way to understand thecomposition law of integral binary quadratic forms throughwhat he calls the ‘cubes of integers’. The goal of this articleis to introduce the reader to Bhargava’s cubes and this newcomposition law, as well as to relate it to the composition lawas it is known classically. We will present a historical expositionof the subject, from Gauss to Bhargava, and see howthe different formulations of the composition laws are equivalent.