A nano is one billionth.  (10 -9) A nanometer is 1/100,000,000.  Viruses and bacteria, DNA, molecules and so many other tiny entities are measurable on the nano scale.  When something so small that the eye cannot see it, can be measured, you can find new uses for it.  Nanotechnology uses the nano to measure tiny particles. It finds new ways to use what we already have.  For instance, scientists are looking at ways to use the nano to get more energy from fossil fuels and to develop new sources of energy.  In the CASE of gasoline production, use of the nano scale to get more and cleaner gas from each barrel of oil, makes us less dependent on oil rich countries and opens the door to creating fuel sources that are eco-friendly, and available everywhere for everyone.