  An exposition is made of recent developments using techniques of unitary
chiral perturbation theory, $U \chi P T$, which allows one to extend
predictions using chiral Lagrangians to higher energies than ordinary chiral
perturbation theory, including the region of low lying mesonic and baryonic
resonances, some of which are dynamically generated in the approach. Results
for meson meson scattering, pion and kaon form factors and meson baryon
scattering are shown. Applications are done for nuclear problems showing the
results for the kaon and eta selfenergies, phi renormalization in a nuclear
medium and $\sigma$ renormalization in the medium, comparing results with
recent experiments.
