  The Compact Muon Solenoid (CMS) experiment at LHC features the largest
Silicon Strip Tracker (SST) ever build. This device is immersed in a 4T
magnetic field and, in conjunction with a Pixel system, it allows the momentum
of the charged particles to be measured and the heavy-flavour final states to
be tagged despite the hostile radiation environment. The impact of operating
conditions and physics requirements on the SST layout and design choices is
discussed and the expected performances are reviewed. The SST collaboration is
now facing the production of the ~15000 modules and their assembly into the SST
substructures. A status is given.
