This book covers the current communication architectures that are implemented in manufactured systems-on-chip, as well as those that are being proposed to overcome the existing limitations. The text addresses well-established communication buses and less-common networks on chip, along with modern technologies that propose the use of carbon nano tubes and optical links to speed up data transfer and increase both security levels and quality of service. Contributors address on-chip transaction security involving critical information and the mechanisms to protect from an external attack, examining different communication protocols and their impact on system performance.