One nanometer is one billionth of a meter. Nanotechnology gives us the ability to manipulate matter one atom or molecule at a time. This technology could lead to a future of dramatic breakthroughs. For example, molecular computers could store the equivalent of the U.S. Library of Congress in a device any of us could wear. Nanostructures are at the confluence of the smallest human-made devices and the large molecules of living systems.
Individual atoms are a few tenths of a nanometer.
To use another comparison, DNA molecules are about 2.5 nanometers wide. Biological cells, such as red blood cells, have diameters in the range of thousands of nanometers. Microelectromechanical systems are now approaching this same scale. This suggests a most exciting prospect. We are now at the point of being able to connect machines to individual living cells.