An introduction to the world of quarks and leptons, and of their interactions governed by fundamental symmetries of nature, as well as an introduction to the connection that exists between worlds of the infinitesimally small and the infinitely large. The book starts with a simple presentation of the theoretical framework, the so-called Standard Model, which evolved gradually since the 1960's. This is followed by its main experimental successes, and its weaknesses and incompleteness. We proceed then with the incredible story of the Large Hadron Collider at CERN - the largest purely scientific project ever realized. What follows is the discussion of the conception, design and construction of the detectors of size and complexity without precedent in scientific history. The book summarizes the main physics results obtained firstly during the initial phase of operation of the LHC, which culminated in the discovery of the Higgs boson in 2012 (the Nobel Prize in Physics in 2013). This is followed by the results obtained in subsequent years up to 2020, consolidating and expanding these findings. These successes have undoubtedly made CERN the focal point, both of intellectual endeavor and technological innovation in this domain of science. In the last chapter we describe the plans for LHC for the next 15 years and the possible evolution of the field and collider projects considered. The authors are researchers from CNRS, CEA, and CERN, all fully engaged in the LHC program: D Denegri in the CMS experiment, C Guyot, A Hoecker and L Roos in the ATLAS experiment. Some of them are involved since the inception of the project. They give a lively inside view of this amazing scientific and human adventure. Readership: Physics students as well as science enthusiasts. "This book presents what is beyond doubt the largest purely scientific project ever, the LHC — the Large Hadron Collider at CERN — and associated experiments ATLAS, CMS, LHCb and ALICE, culminating with the discovery of the Higgs boson in summer 2012. [ ] Such discoveries, as those of the W, Z and now Higgs, are real landmarks in the history of sciences." -- Foreword by Carlo Rubbia (Nobel laureate in Physics, 1984 Daniel Denegri was born in Split, Croatia, from a Croatian father and French mother; today he is research director emeritus at the CNRS in France. He studied physics at the University of Zagreb, Croatia, and subsequently obtained a PhD in particle physics at the Johns Hopkins University in Baltimore, USA. In 1971 he started working at the CEA research center in Saclay near Paris. In 1982/83 he played a most direct role in the discovery of the W and Z bosons in the experiment UA1. In 1986 he left CEA and CNRS to work at CERN. In 1989/90 he together with Carlo Rubbia initiated the LHC project, being one of the three coordinators of the physics studies in evaluating the discovery potential of the LHC. In 1990/91 he was one of the founding fathers of the CMS experiment with Michel Della Negra and Jim Virdee, being physics coordinator of the collaboration for 14 years. He had an active part in the discovery of the Higgs boson in 2012 and is now investigating the future physics program of the LHC. Claude Guyot is a researcher at the Research Institute on the Fundamental Laws of the Universe (IRFU) at the Saclay-CEA Centre. After a PhD in particle physics in 1984 on neutrino oscillations based on results from the CDHSW experiment at CERN, he continued studying neutrino nucleon interactions investigating electroweak interactions and the internal structure of nucleons. While studying the violation of CP and T symmetries in an experiment with neutral kaons, in 1991 he joined a group of physicists that would subsequently found the ATLAS experiment at the LHC. He was one of the physicists at the origin of the ATLAS muon spectrometer, in particular its large superconducting toroidal magnet. Since 2011 he is the head of the ATLAS group at the CEA-Saclay Centre. Andreas Hoecker was born and studied physics in Germany. He did his PhD at the Laboratoire de l'Accelerateur Lineaire in Orsay near Paris on studies of tau lepton properties and of strong interactions, using data from the ALEPH experiment at the LEP collider at CERN. After his PhD, in 1997 he joined the CNRS and took part in the BaBar experiment at Stanford, USA, where he spent two years studying the violation of the matter antimatter–symmetry. Upon his return to Orsay, in 2005 Andreas Hoecker went to CERN on a permanent research physicist position. Since then he works on the ATLAS experiment, where he contributed in various domains of detector operation and physics data analysis, more specifically in the search for supersymmetry and the discovery of the Higgs boson. He was physics coordinator of the ATLAS collaboration in 2014 and 2015, and was elected deputy spokesperson of ATLAS in 2016. Lydia Roos is research director at the CNRS. During her PhD studies in Marseille she studied properties o