  We will revise one of the methods given in the literature to determine the
necessary and sufficient conditions that the parameters must satisfy to have a
stable scalar potential in the general two-Higgs doublet model. We will give a
procedure that facilitates finding the conditions for stability of a scalar
potential. The stability guarantees that the scalar potential has a global
minimum, that is, the potential is bounded from below, which is a necessary
condition to implement the spontaneous gauge-symmetry breaking in the models.
