Nanoscience is the science of the extremely small. How small? A nanometer is a millionth of a millimeter -- about the size of some big single molecules such as the protein enzymes in our bodies. For perspective, a red blood cell is about six thousand nanometers across and a human hair typically 20,000-100,000 nanometers.
So nanoscience is indeed science at extremely small scales. But why is this important? The incredible advances in computer power come largely from making the transistors of microelectronic circuits ever smaller. In medicine, advances at the nanoscale let us make interventions at the natural size scale of living cells themselves. Ultimately, mastering how to build things at the scale of atoms and molecules may allow us to start mimicking some of the clever things that nature achieves with her own “natural nanotechnology,” which may lead to finding better and cheaper ways of harvesting sunlight for energy, or detecting and eliminating pollutants in water and air.