In the course of this book, we have often encountered nano-machines and nanotechnologies, and the time has come to clarify some things about them. First of all, a dictionary definition: nanotechnology consists in the manipulation of matter at the atomic and molecular levels. In particular, the extended version of this concept speaks of precise atomic and molecular manipulation, with the aim of producing objects for everyday use – a hypothetical technology also known as “molecular nanotechnology.” The National Nanotechnology Initiative, the American federal program for the development of nanotechnologies, defines nanotechnology as the manipulation of matter in which at least one of the dimensions, i.e., length, width or height, is between one and one hundred nanometers. A nanometer corresponds to a billionth of a meter – more or less the order of magnitude of molecules, so to speak. You can already imagine how the term “nanotechnology” is currently an umbrella under which very different ideas and practices are included. So, we ask: what are nanotechnologies made of now? What fields do they include, what devices do they use, in short, what do they do and what do they produce? Let’s take a brief look at this.