What are the key features and implications of the two-Higgs-doublet model in particle physics?

The two-Higgs-doublet model in particle physics involves the presence of two Higgs doublets instead of one, leading to the existence of additional Higgs bosons. This model can provide a solution to certain theoretical issues in the Standard Model, such as the hierarchy problem. The implications of this model include the potential for new particles and interactions beyond those predicted by the Standard Model, which could be observed in experiments at high-energy colliders like the Large Hadron Collider.