W physics at LEP

Studying the properties of the W boson plays a key role in precision tests of the Standard Model. The key measurements performed over the last decade will be reviewed. W-pair and single-W cross-sections and W decay branching fractions are determined and agree well with theoretical predictions. Including the analysis of differential distributions, trilinear and quartic couplings of the W boson to the other gauge bosons are extracted. A precise measurement of the mass and width of the W boson is presented. The W mass is in good agreement with the one obtained indirectly from an analysis of other electroweak data measured at LEP and SLD. Some of the results presented in this article are preliminary.