It is widely accepted that nanonetworks will enable a plethora of long-awaited applications, ranging from healthcare to homeland security, industrial development and environmental protection. Enabling communication among nanomachines is still a major challenge. While it is acknowledged that there is still a long way to go before having a fully functional nanomachine, this book makes the case that hardware-oriented research and communication-focused investigations will benefit from being conducted in parallel from an early stage. Fundamentals of Electromagnetic Nanonetworks in the Terahertz Band defines the first steps towards enabling electromagnetic communication among nanomachines in the Terahertz Band (0.1-10 THz). The starting point is the development of novel graphene-based plasmonic nano-antennas, which efficiently operate in the Terahertz Band. The authors have developed a novel Terahertz Band channel model and investigated the potential of this frequency band by means of a channel capacity analysis. In light of the channel peculiarities and the nanomachine capabilities, they put forward a set of communication mechanisms for nanonetworks, which include femtosecond-long pulse-based modulations, low-weight channel coding schemes, a new symbol detection scheme at the receiver, and a new medium access control protocol for nanonetworks. In addition, the book analyzes the performance of perpetual nanonetworks by developing a joint energy harvesting and energy consumption model for self-powered nanomachines. Finally, an emulation platform has been developed to simulate a one-to-one nano-link between nanomachines and validate the developed models.