Reverse electrodialysis (RED) technology has grown significantly in the last decade, gaining a fast increase in its technology readiness level and presenting some interesting examples of RED pilot systems operating under very different real environments. In this chapter, an overview of technological developments and piloting examples are reported. In particular, a short introduction is given on the historical trend of RED technology growth, followed by a careful analysis of which feed solutions can be adopted and how these can affect the process performance, potentials, and applications. Most prominent fluid dynamics aspects for the RED process are presented, highlighting how these can influence the design and operation of RED systems, being able to affect the overall performance of a RED plant. For the first time, two practical experiences of RED technology piloting are analysed: the Afsluitdijk pilot plant in The Netherlands (. Blue Energy project), operating with seawater and river water, and the Marsala pilot plant in Italy (. REAPower project), operating with concentrated brines and saline waters. The main achievements, progresses, growth directions and world key actors in the technology development will be underlined. Finally, the envisaged R&D routes and perspectives for the future of RED technology development will be outlined.