The free neutron decay offers a powerful method to test the Standard Model and search for new physics; for example, the neutron lifetime and decay correlations provide essential inputs for the precise extraction of the CKM matrix element Vud and for the search of exotic currents in charged weak interactions. Carefully comparing the experimental outcomes of different decay correlations even allows us to go beyond the effective field theory description of new physics and probe light degrees of freedom. In this talk I will briefly review the few anomalies we observed in neutron decay experiments and describe several recent improvements in theory for a better analysis of the experimental results.