Here is a comparison - A nanoparticle size is compared to an ant as an ant is compared to the Indianapolis Motor Speedway.
More relative sizes: (nm is nanometer)
The head of a pin 1,000,000 nm across You can see these with your eyes unaided
The page of a book 100,000 nm thick
A human hair 40,000 nm thick
A red blood cell 7,000 nm across You can see these using a light microscope
DNA molecule 2 nm wide
Most atoms 0.1–0.2 nm
During the next 20 years, nanotechnology will touch the life of nearly every person on the planet. Below is a guide to uses for some of these nano wonders.
Quantum dots - are made of semiconducting molecules, they glow fluorescently and are great at absorbing light. Used for more efficient solar cells and microscopy dyes for cell biology research.
Silica - silicon dioxide nanoparticles enable so-called shear thickening fluid to become stronger on impact. Used for stab-resistant Kevlar for body armor.
Zinc oxide - tiny crystals stop UV radiation and are toxic to microscopic life. Used for UV-resistant packaging, sunscreen, and paint and textiles that inhibit bacteria and fungi.
Nano barcodes - bits of various metals linked into tiny wires make good tags for microscopic things. Used for tracking DNA and cells.
Lithium iron phosphate - particles organize themselves into an anode, which allows batteries to charge and deliver power extremely quickly. Used for electric cars, power tools.
Iron oxide - mini magnets can stick to certain chemicals. Used for steering cancer drugs and genes to targets in the body while minimizing collateral damage. Sometimes smaller is better.