Single atom/molecule manipulation with a scanning-tunneling-microscope (STM) tip is an innovative experimental technique of nanoscience. Using a STM tip as an engineering or analytical tool, artificial atomic-scale structures can be fabricated, novel quantum phenomena can be probed, and properties of single atoms and molecules can be studied at an atomic level. The STM manipulations can be performed by precisely controlling tip-sample interactions, by using tunneling electrons, or electric field between the tip and sample. In this article, various STM manipulation techniques and some of their applications are described, and the impact of this research area on nanoscience and technology is discussed. (c) 2005 American Vacuum Society.