Physics is an experimental science. Experiments are usd to prove or reject theories. Therefore, we will discuss how our understanding of the subatomic world has been shaped by ground-breakingand fundamental experiments, each of which throws light on one major aspects: the structure of the proton, the existence of weakly interacting particles, the second and third generations of quarks and leptons, W and Z bosons as mediators of electroweak interactions and important ingredients of the "Standard Model" of elementary particles, the violation of fundamental symmetries such as parity and CP violation, and the observation of neutrino oscillations. Current experimental efforts are directed towards discovering the remaining piece in the Standard Model - the Higgs particle - and fexploring postulated physical phenomena beyond the Standard Model, such as "supersymmetric" particles.
