A nanometer is one billionth of a meter, or 1×10−91\times 10^{-9}1×10−9 meters. It is extremely small—much smaller than what the human eye or even a light microscope can see. To put it in perspective, a nanometer is about 1 millionth of a millimeter, and typical objects on the nanoscale range from 1 to 100 nanometers, such as some viruses, DNA strands (about 2.5 nm wide), and nanoparticles. For comparison, a human hair is about 60,000 to 100,000 nanometers wide, illustrating how incredibly tiny a nanometer is.
