Review of Rare and Forbidden τ Decays

This is a review of rare and forbidden decays of the τ lepton. For the rare decays, this includes new results on the chiral anomaly decay τ^- → π^-ηπ⁰ν _τ, new upper limits on the second-class-current decay τ^- → π^-ην _τ, and the observations of the Cabibbo-suppressed decay τ^- → K^-ην _τ and the internal conversion decay τ¯→ π¯ npi=π⁰v _π. For the forbidden decays, there are new upper limits on the radiative decays τ^- → e^-γ and τ^- → μ^-γ. Some forbidden decays which have not been previously searched for are also suggested.