  Within the framework of the Standard Model, the scale of electroweak symmetry
breaking is unstable to radiative corrections. We discuss two broad classes of
models of new physics (one with a strongly interacting and the other with a
perturbatively coupled electroweak symmetry breaking sector) in which this
stability is restored. After reviewing experimental constraints on these, we
discuss the implications of these types of models for experiments, both at
currently operating colliders as well as the next generation of colliders under
consideration for construction. Other extensions of the Standard Model are
briefly alluded to.
