  The trigger system of the LHCb experiment is discussed in this paper and its
performance is evaluated on a dataset recorded during the 2012 run of the LHC.
The main purpose of the LHCb trigger system is to separate heavy flavour
signals from the light quark background. The trigger reduces the roughly 11MHz
of bunch-bunch crossings with inelastic collisions to a rate of 5kHz, which is
written to storage.
