CMS muon system performance

The CMS muon system is taking cosmic data since 2006 and is using them to study the performance of the three different detector technologies and triggers (drift tube, cathode strip chambers and resistive plate chambers). The muon system is described placing emphasis on the software tools that were developed and used to take data and to study, online and offline, the performance of the muon system. The results obtained analyzing up to 300 millions of cosmics acquired with the CMS detector will be described.