Nanotechnology corresponds to the manipulation of objects that are as small as a few atoms or molecules. This technology has enabled us to produce nanomaterials, namely materials of nanometric size in at least one of their dimensions. This very small size confers new properties or particular behaviors that are very useful in new technological applications. This book describes the exploration of the properties of biological systems on the nanometer scale (especially with AFM), the toxicological issues associated with the development of nanotechnology and the need to develop socially responsible research in this emerging field.