The Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) is undertaking a Phase II upgrade program to face the harsh conditions imposed by the High Luminosity LHC (HL-LHC). This program comprises the installation of a new timing layer to measure the time of passage of minimum ionizing particles (MIP) with a time resolution of 30 ps. This MIP Timing Detector (MTD) will be composed of a central barrel timing layer (BTL) covering a pseudorapidity range up to 1.4, and a endcap timing layer (ETL) reaching a pseudorapidity of 3. The BTL will consist of LYSO:CE crystals while the ETL will be instrumented with Low Gain Avalanche Detectors (LGAD). The time information of the tracks will improve the rejection of spurious tracks and vertices, will allow to perform particle identification based on the time-of-flight and will bring unique physics opportunities in interesting signatures such as those including long-lived particles.