The history of information and communications technologies (ICT) has been paved by both evolutive paths and challenging alternatives, so-called emerging devices and architectures. Their introduction poses the issues of state variable definition, information processing, and process integration in 2D, above IC, and in 3D. This book reviews the capabilities of integrated nanosystems to match low power and high performance either by hybrid and heterogeneous CMOS in 2D/3D or by emerging devices for alternative sensing, actuating, data storage, and processing. The choice of future ICTs will need to take into account not only their energy efficiency but also their sustainability in the global ecosystem.