Preparation and commissioning of LHCb for the Run II of LHC

The LHCb experiment has performed very well during the Run I of the LHC, producing a large number of relevant physics results on a wide range of topics. The preparation and commissioning of the LHCb experiment for Run II is discussed here, with special emphasis on the changes in the trigger strategy and the addition of a new subdetector to improve the physics reach of the experiment. An overview of the commissioning with the first collisions delivered by the LHC is also included.