  In this paper we describe the history of the LHCb experiment over the last
three decades, and its remarkable successes and achievements. LHCb was
conceived primarily as a b-physics experiment, dedicated to CP violation
studies and measurements of very rare b decays, however the tremendous
potential for c-physics was also clear. At first data taking, the versatility
of the experiment as a general-purpose detector in the forward region also
became evident, with measurements achievable such as electroweak physics, jets
and new particle searches in open states. These were facilitated by the
excellent capability of the detector to identify muons and to reconstruct decay
vertices close to the primary pp interaction region. By the end of the LHC Run
2 in 2018, before the accelerator paused for its second long shut down, LHCb
had measured the CKM quark mixing matrix elements and CP violation parameters
to world-leading precision in the heavy-quark systems. The experiment had also
measured many rare decays of b and c quark mesons and baryons to below their
Standard Model expectations, some down to branching ratios of order 10-9. In
addition, world knowledge of b and c spectroscopy had improved significantly
through discoveries of many new resonances already anticipated in the quark
model, and also adding new exotic four and five quark states.
