This final book provides an introduction to this rapidly developing field, setting nanotechnology in the context of the attention it is receiving from governmental and non-governmental agencies as well as the media. The book considers what it means to work at the nanoscale and describes two types of development in this very interdisciplinary the nanoscience of materials and the creation of bio-nanotechnological devices which could be inserted into living systems. The way in which the risks are assessed is discussed, as are the concerns about the ethical issues and uncertainties involved. The Conclusion to the course then revisits several themes-related questions from the perspective of having studied all seven topics of S250.