  Many experiments are underway in the world to search for a non-zero electric
dipole moment (EDM) of a particle with spin 1/2 such as the neutron or the
electron. Finding an EDM would reveal new sources of CP violation. EDM
measurements are motivated by the high sensitivity to new physics beyond the
Standard Model. They are relevant to find the explanation for the
matter-antimatter asymmetry of the Universe. A variety of programs with
different systems are being pursued, with free neutrons, diamagnetic atoms,
paramagnetic systems, and charged particles in storage rings. This article
presents a basic introduction of the subject and attempts to compile the
ongoing projects.
