It has long been a goal of particle physics to find a single unified mathematical description of all fundamental measurable phenomena. The previous chapters have outlined the concepts and ideas behind such a comprehensive theory, namely the Standard Model of particle physics. It describes three of the four known fundamental forces of Nature in a fully consistent model: the electroweak interaction, which unifies electromagnetism and the weak force, and the strong force. Together with the independent description of gravity by general relativity, this allows us to describe "in principle" all known phenomena that can be measured in precision experiments on Earth. This represents a historically unique situation and a major cultural achievement. This chapter presents the most outstanding experimental steps that established the Standard Model as the description of the forces in the microcosm. Despite the great successes of the Standard Model, physicists have still far from completed their work. They know that the Standard Model cannot be the "Theory of Everything". The ever more precise experiments in cosmology demand an extension or a complete replacement of the Standard Model. They require an explanation for dark matter through a new particle, as well as a mechanism to account for the observed difference in the amount of matter and antimatter in the Universe. Additionally, precision measurements testing the Standard Model's own predictions, including anomalous magnetic moments or rare meson decay observations, show deviations in some areas that might be random but could also indicate a path beyond the Standard Model. Researchers are therefore diligently searching for the precise point where the Standard Model no longer accurately describes the nature of the microcosm. They are in pursuit of a future groundbreaking discovery.