  In the two Higgs doublet model, there is the possibility that the vacuum
where the universe resides in is metastable. We present the tree-level bounds
on the scalar potential parameters which have to be obeyed to prevent that
situation. Analytical expressions for those bounds are shown for the most used
potential, that with a softly broken $Z_2$ symmetry. The impact of those bounds
on the model's phenomenology is discussed in detail, as well as the importance
of the current Large Hadron Collider results in determining whether the vacuum
we live in is or is not stable. We demonstrate how the vacuum stability bounds
can be obtained for the most generic CP-conserving potential, and provide a
simple method to implement them.
