  Effective Lagrangians represent an important, model independent tool for
studying physics beyond the Standard Model, via its impact on electroweak scale
observables. In particular, two different effective descriptions may be
appropriate, depending on how the electroweak symmetry breaking is realized at
high energies: a linear effective Lagrangian is best suited in presence of
linear dynamics, while a non-linear -chiral- one is more pertinent for
scenarios featuring a non-linear realization. In this talk I will present a few
examples of low-energy signals that differentiate the phenomenology of the two
descriptions, thus providing a powerful insight into the nature of the Higgs
boson.
