In 2010 the LHC accelerator collided protons and lead ions at unprecedented high energies. Outstanding progress was made in operating the accelerator with very good performance. The Compact Muon Solenoid (CMS) experiment, one of the two large general-purpose experiments, also performed very well, close to the ambitious design performance set down some fifteen years ago. Physics measurements are confronting, more and more precisely, the predictions of the Standard Model of particle physics, whilst looking for new physics. CMS is well set to make widely expected ground-breaking discoveries. Potential discoveries include new forces of nature, new dimensions and new states of matter. CMS is designed to operate in a very harsh environment created by hundreds of billions of particles produced every second, and to register with high accuracy the passage and energies of all these particles, thus demanding huge data collection, transfer and processing rates on a scale greater than ever previously attempted. CMS comprises over 3500 scientists and engineers from over 180 institutions in 38 countries. The seminar will briefly recall the physics potential of the LHC, outline some of the challenges faced during the construction of CMS, its operation and performance, the first physics results, and the outlook.