Power beaming is the efficient point-to-point transfer of electrical energy across free space by a directive electromagnetic beam. This paper clarifies the basic principles of power beaming in simple terms, and proposes a benchmarking methodology for improving the comparative assessment of power beaming systems and technology. An in-depth historical overview tracing the worldwide progress in microwave and millimeter wave (mmWave) experimental demonstrations over the past 60 years shows clear evidence of a significant increase in activity during the last 5 years. In addition, a review of progress in scalable rectenna arrays for the reception of microwave power beaming shows sufficient maturity for new research to initiate on the ruggedizatio...