Exotic Recombination

I review few examples of the numerous physical processes that might change the standard model of recombination. The high precision of current and future CMB data may allow the detection of these processes, that leave recognizable imprints on the angular power spectra. I review some of the results obtained in constraining i) a variation of the gravitational constant G ii) the presence of extra-sources of energetic photons in the primeval plasma and iii) annihilation of dark matter particles.