Abstract
The scanning tunneling microscope (STM) has proven to be an unsurpassed instrument for studying surfaces with sub-nanometer resolution in all three spatial dimensions. The same circumstances that permit the STM to image with atomic resolution also allow it to function as a highly localized probe capable of exerting human influence upon regions of only nanometers in extent. Demonstrations of the STM's ability to modify matter at the nanometer scale give evidence of its promise as a tool for nanofabrication applications. In addition to presenting some recent results of STM modifications of Au and graphite substrates, this paper introduces a system for classifying the various mechanisms by which an STM may induce modifications, and classifies published and new experimental observations within this framework.