Review of LHC Run 2 Machine Configurations

During LHC Run 2, the LHC machine configuration evolved significantly. Starting from a very careful approach in 2015, with the priority on stability and ease of commissioning, where the limits of operation at the higher energy of 6.5 TeV were not well known, the machine settings were pushed further during the run, which ended with an optimized 2018 scenario with excellent performance. In this contribution, an overview is given of the evolution of different machine parameters, in particular the collimation settings, aperture and $\beta$$^{*}$ , which are tightly linked to the peak luminosity performance of the machine. The key changes and the reasons behind are reviewed, as well as lessons learned for the future.