Book excerpt: An accessible introduction for electronic engineers, computer scientists and physicists. The overview covers all aspects from underlying technologies to circuits and systems. The challenge of nanoelectronics is not only to manufacture minute structures but also to develop innovative systems for effective integration of the billions of devices. On the system level, various architectures are presented and important features of systems, such as design strategies, processing power, and reliability are discussed. Many specific technologies are presented, including molecular devices, quantum electronic devices, resonant tunnelling devices, single electron devices, superconducting devices, and even devices for DNA and quantum computing. The book also compares these devices with current silicon technologies and discusses limits of electronics and the future of nanosystems.