This document discusses nanotechnology and its applications. It defines nanotechnology as manipulating matter at the nanoscale, between 1-100 nm. Some key applications mentioned include using titanium dioxide and zinc oxide nanoparticles in sunscreens for UV protection, using titanium dioxide nanocrystals in photocatalysis and self-cleaning surfaces, and using atomized aluminum nanoparticles as propellant in rocket fuel. The document also discusses nanofabrication methods like top-down approaches that begin large and reduce size, and bottom-up techniques that build up from atoms and molecules.