  The phenomenon of neutrino oscillations has been established as the leading
mechanism behind neutrino flavor transitions, providing solid experimental
evidence that neutrinos are massive and lepton flavors are mixed. Here we
review sub-leading effects in neutrino flavor transitions known as non-standard
neutrino interactions, which is currently the most explored description for
effects beyond the standard paradigm of neutrino oscillations. In particular,
we report on the phenomenology of non-standard neutrino interactions and their
experimental and phenomenological bounds as well as future sensitivity and
discovery reach.
