The CPLEAR experiment

LEAR offered unique opportunities to study the symmetries which exist between matter and antimatter. At variance with other approaches, CPLEAR was an experiment devoted to the study of CP, T and CPT symmetries in the neutral-kaon system. A number of measurements allowed us to specify with high precision and in a rather complete way, the parameters which describe the time evolution of the neutral kaons and their antiparticles, including decay amplitudes, and the related symmetry properties. A brief account of the main features of the experiment and its performances is given here, together with the results achieved on T and CPT symmetries, including tests of Quantum Mechanics.