The world in the nano-scale

Nanotechnology deals with research and transformation of substances and systems, the individual atom size of which is not more than 100 nanometers.

A nanometer (nm) is one millionth of a millimeter. In a piece of metal, a nanometer is almost the length of four adjacent atoms. A skin cell is of the size of about 10,000 nm, a virus 100 nm, a nanotube 1 - 50 nm.
 

Nanoparticles

Nanoparticles are groups of a few to some thousand atoms or molecules. They have special chemical and physical properties, which clearly differ from those of solids or bigger particles. More importantly, they react more vigorously with other substances and can thus lend special properties to these substances.