The Compact Muon Solenoid is a detector designed for the Large Hadron Collider. High particle rates combined with a magnetic field of 4 T make particle tracking a challenge. The baseline is to use silicon pixel and microstrip detectors and microstrip gas chambers. This note focuses on the barrel part of the silicon tracker. It is made of 816 modules (368 single-sided and 448 double-sided) arranged in three layers. The basic module consists of four 300 μm thick silicon microstrip detectors, glued together to obtain a total active area of 51.2 × 250 mm 2. The choice of silicon strip detector is based primarily on three elements: AC-coupling integrated on the detector substrates; polysilicon resistors used as bias elements; p-stop isolation to control the interstrip resistance of the ohmic side in double-sided detectors. A review of beam test results is described for different parts of the CMS barrel tracker.