Abstract—Recent advances in nano-materials and nanotechnology have paved the way for building integrated devices with a nanometric size, named nano-nodes. These nano-nodes are composed of nano-processor, nano-memory, nano-batteries, nano-transceiver, nano-antenna and nano-sensors, which operate at nano-scale level. They are able to perform simple tasks, such as sensing, computing and actuation. The interconnection between microdevices and nanonodes/nanosensors has enabled the development of a new network standard, called Wireless Nano-Sensors Network (WNSN). This paper provides an in-depth review of WNSN, its architectures, application areas, and challenges, which need to be addressed, while identifying opportunities for their implementation in various application domains.