W Physics at LEP

In five years of operation (1996-2000) the four LEP2 experiments collected roughly 3 fb-1 of data from e+e- collisions at centre-of-mass energies between 161 and 207 GeV, yielding a total of about 40000 W-pair events. The analysis of the LEP2 W-pair production rates and kinematics has allowed fundamental new measurements of the electroweak model to be performed, most notably: (i) the first determination of gauge boson self couplings, (ii) direct measurements of W decay couplings to all fermions, and (iii) a direct measurement of the W mass with a 40 MeV precision, comparable to hadron collider and indirect determinations.