The LHCb Trigger: Present and Future

LHCb is a single arm spectrometer covering the pseudo-rapidity range between 1.9 and 4.9, and has been optimised to perform flavour physics measurements at the LHC. The present two stage trigger system is able to select charm and beauty decay products with high efficiency due the highly inclusive approach of triggering on partially reconstructed decays and the use of a novel multivariate classifier at the second stage. The trigger can select both leptonic and purely hadronic decays. The performance of the trigger is determined from the data itself without having to rely on Monte-Carlo simulation and is presented. LHCb has recently submitted their upgrade LOI, which mainly aims at profiting from much larger luminosities by moving towards a single fully software based trigger. The upgrade strategy and expected performance are presented.