It is a long and complicated chain, from the signal created by a particle in a detector to a plot which shows a final physics result. In these two lectures I will explain the basic elements of this chain, such as the momentum measurement of a charged particle from its signals in a tracking detector, or the reconstruction of a quark's flight direction even if quarks are not directly observable.
Prerequisite knowledge: Basic introduction to particle physics (the Standard Model, its particles and forces); basic introduction to particle detectors.