In the realm of the dwarfs
Nanotechnology is the science of "the small". The prefix "nano" originates from the Greek and and was derived from the word "nanos" which means "dwarf". One nanometer is one billionth of a meter (10-9 m) or one millionth of a millimeter (10-6 mm). The nano cosmos is the world of atoms and molecules.
If three gold atoms are placed side by side, their overall length equals one nanometer. Obviously, such dimensions are invisible to the naked eye and specialised instruments are necessary to visualise structures at the nanoscale. Since 1980, specific microscopes are available which allow us to investigate and even manipulate nanostructures.
Naturally occurring and out of the lab
Nanotechnology on the one hand aims to building things at ever smaller sizes and with increased precision. On the other hand, nanotechnology grants us access to the world of atoms and molecules. The manipulation of matter on the atomic or molecular level allows synthesising new materials or systems of materials.
Nanomaterials can either be of natural origin or engineered. In nature, volcano ashes or the smoke of wood fires contains soot particles of nanometer size. Many biological or chemical particles such as small lipid droplets in milk or proteins in the blood are nano-sized.
However, there are also human-made (engineered) nanomaterials. Such engineered nanomaterials may either be intentionally synthesised (e.g. in the laboratory) or emerge unintentionally (e.g. upon burning diesel fuel in combustion engines). These particles are thus called manufactured or synthetic nanomaterials.
New properties through smallness
Nanomaterials often show new physical and chemical properties, compared to the corresponding bulk materials. If a material such as, e.g., metallic aluminium is milled down to the nanoscale, the resulting nanoparticles often show new properties. The fine nanopowder possesses different physical properties although the substance is the very same from a chemical point of view.
Aluminium foil is well-known to be chemically very stable and unreactive in its bulk form as used to wrap-up food in the kitchen. On the contrary, nanosized aluminium nanoparticles with a diameter of 80 nm are highly reactive and they are used as a rocket fuel.