The quantitative determination of the properties of micro- and nanostructures is essential in research and development. Here, peer-reviewed papers are presented with contributions for the NanoScale 2004 seminar at the Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany, in March 2004. Topics include problems of quantitative measurement as well as methods of calibration, correction and instrumentation. The seminar stimulates the exchange of information between users in science and industry and manufacturers of the relevant hard- and software.