What is time reversal and what it cannot do?

In electromagnetics, time reversal was first examined in the fifties of the twentieth century. Whereas in acoustics, time reversal was first experimented in the nineties. In the current literature on electromagnetics, antennas and propagation and wireless communications, time reversal is frequently referred to as a technology that first appeared in acoustics and was then borrowed in electromagnetics. This referral totally ignores the true history of time reversal in electromagnetics, affecting dramatically the evolution of the subject as a reliable technology. A clarification of the true meaning of time reversal in electromagnetics and its real capabilities is given in this paper. This is done through a critical analysis of the recent as well as the old literature on the topic.