The synthesis of semiconductor nanowires has been studied intensively worldwide for a wide spectrum of materials. Such low-dimensional nanostructures are not only interesting for fundamental research due to their unique structural and physical properties relative to their bulk counterparts, but also offer fascinating potential for future technological applications. Deeper understanding and sufficient control of the growth of nanowires are central to the current research interest. This Review discusses the various growth processes, with a focus on the vapor-liquid-solid process, which offers an opportunity for the control of spatial positioning of nanowires. Strategies for position-controlled and nanopatterned growth of nanowire arrays are reviewed and demonstrated by selected examples as well as discussed in terms of larger-scale realization and future prospects. Issues on building up nanowire-based electronic and photonic devices are addressed at the end of the Review, accompanied by a brief survey of recent progress demonstrated so far on the laboratory level.