Twenty Years of Searching for the Higgs Boson: Exclusion at LEP, Discovery at LHC

The 40 years old Standard Model, the theory of particle physics, seems to describe all experimental data very well. All of its elementary particles were identified and studied apart from the Higgs boson until 2012. For decades many experiments were built and operated searching for it, and finally, the two main experiments of the Large Hadron Collider at CERN, CMS and ATLAS, in 2012 observed a new particle with properties close to those predicted for the Higgs boson. In this paper we outline the search story: the exclusion of the Higgs boson at LEP, the Large Electron Positron collider, and its observation at LHC