Many new tests of gravity and, in particular, of Einstein's general relativity theory will be carried out in the near future: the Lense-Thirring effect and the equivalence principle will be tested in space. Moreover, gravitational waves will be detected, and new atomic interferometers and clocks will be built for measurements in gravitational and inertial fields. New high-precision devices have made these experiments feasible. They will contribute to a better understanding of gravitational physics. Both experimental developments and the theoretical concepts are collected in this volume....