Nanotechnology refers broadly to a field of applied science and technology whose unifying theme is the control of matter at the molecular level on scales less than 1 micrometer, usually 1 to 100 nanometers, and the manufacture of devices within that size range. A nanometer is one billionth of a meter (0.000000001 m).

Matters such as gases, liquids, and solids can exhibit unusual nano-scale physical, chemical, and biological properties that differ significantly from the properties of bulk materials and individual atoms or molecules. Some nanostructured materials are stronger or have different magnetic properties compared to other shapes or sizes of the same material. Others are better at conducting heat or electricity. They can become more chemically reactive or reflect better light or change color as their size or structure is altered.