The book reviews the current status of tau physics. It addresses the properties of the tau lepton and summarizes results achieved with tau leptons in the fields of precision tests of the Standard Model, investigations of the strong interaction and many searches for new physics beyond the scope of the Standard Model.

The ? lepton and the third family.- Experimental aspects.- The static properties of the ?.- Electroweak physics at the Z0 pole.- Strong interactions in ? decays.- ? physics at hadron colliders.- The ? neutrino.- The lorentz structure of the charged current.- Searching for CP violation.- Rare and forbidden decays.- Summary and outlook.- Physics with tau leptons.- Physics with tau leptons.