Nanowires, nanobelts, nanoribbons, nanorods..., are a new class of quasi-o- dimensional materials that have been attracting a great research interest in the last few years. These non-carbon based materials have been demonstrated to exhibit superior electrical, optical, mechanical and thermal properties, and can be used as fundam- tal building blocks for nano-scale science and technology, ranging from chemical and biological sensors, field effect transistors to logic circuits. Nanocircuits built using semiconductor nanowires demonstrated were declared a "breakthrough in science" by Science magazine in 2001. Nature magazine recently published a report claiming that "Nanowires, nanorods, nanowhiskers, it does not matter what you call them, they are the hottest property in nanotechnology" (Nature 419 (2002) 553). There is no doubt that nanowire based quasi-one-dimensional materials will the new focal point of research in the next decades.Volume 1: Metal and Semiconductor Nanowires covers a wide range of ma- rials systems, from noble metals (such as Au,Ag, Cu), single element semiconductors (such as Si and Ge), compound semiconductors (such as InP, CdS and GaAs as well as heterostructures), nitrides (such as GaN and Si N ) to carbides (such as SiC). The 3 4 objective of this volume is to cover the synthesis, properties and device applications of nanowires based on metal and semiconductor materials. The volume starts with a review on novel electronic and optical nanodevices, nanosensors and logic circuits that have been built using individual nanowires as building blocks.