Wireless energy harvesting (WEH) and wireless power transfer (WPT) are two closely related topics: they both employ a critical device – a rectenna, which is defined as the combination of an antenna and a rectifier. It receives RF/microwave waves and converts them into DC energy/power which can then be stored or used by application devices. It is expected this technology would produce higher energy conversion efficiency than photovoltaic technology for electromagnetic waves in the future. Energy conversion efficiency is the critical and most important element for wireless energy harvesting (WEH) and wireless power transfer (WPT). How to design an efficient rectenna is a key challenge since this is a non-linear device whose performance is heavily affected by the input power and the load impedance. WEH is motivated by the demand for a low-cost and low-power supplier for many Internet-of-Things (IoT) devices. The conventional battery is good for many applications, but it has to be changed now and then which means a waste of human resources and materials. Due to the widespread use of wireless systems, a lot of electromagnetic energies are around us and available in the ambiance environment at different frequencies (such as FM, TV, mobile, and Wi-Fi signals). Rectennas, especially broadband rectennas, are the ideal device to harvest these energies. WPT is another major breakthrough that has made wireless charging possible and will enable many more anticipated ubiquitous IoT, EV, and medical applications. Unlike WEH, WPT is normally narrow-band and could be near-field or far-field. Thus the design requirements are different from WEH although they both use rectennas. In this Lecture, we are going to 1) introduce the rectenna and review major historical events and developments; 2) provide a comprehensive review of rectenna designs (including different topologies and their comparison); 3) discuss the state-of-the-art designs (including such as the application of metamaterials and surfaces) and challenges (e.g. how to make it compact and efficient); 4) explain its applications in a range of WEH and WPT, including some very ambitious projects in the world. Furthermore, it will include some life and video demonstrations produced by our research group. Co-sponsored by: Sataracom Montreal Speaker(s): Prof. Yi Huang, Virtual: https://events.vtools.ieee.org/m/351635