[en] The measured properties of the tau lepton and its neutrino are reviewed. A constrained fit to the world data gives a tau branching fraction to an electron plus neutrinos (B/sub e/) of (17.4 +- 2.1)% and B/sub mu//B/sub e/ = 1.07 +- 0.17. New data on the tau → pi nu mode are in agreement with the expected branching fraction. There is evidence for the tau → A₁ nu mode, but the A₁ resonance cannot be conclusively established from the current data. The DELCO experiment establishes the tau mass to be 1782 /sup +2//sub ^-7/ MeV/c² and the nu/sub tau/ mass to be less than 250 MeV/c². It also excludes V + A as a tau - nu/sub tau/ coupling and strongly favors V - A