Book excerpt: One-dimensional (1D) nanostructures, including nanowires, nanotubes and quantum wires, have been regarded as the most promising building blocks for nanoscale electronic and optoelectronic devices. This book presents exciting, state-of-the-art developments in synthesis and properties of 1D nanostructures with many kinds of morphologies and compositions as well as their considerable impact on spintronics, information storage, and the design of field-effect transistors.