Nanotechnology is the fabrication of devices less than 100 nm (nanometers) of size. A nanometer is considered as one billionth of a meter i.e. 10^-9. Therefore, nanotechnology is known as building devices at the size of 10^-9.
Nanotechnology plays an important role in almost all fields like Nano Machines, Nano Particles, Nano Elasticity, Carbon Nanotubes, Nano Robots, Nano Electronics, Nano Manipulator, and Nano Biometrics.
The below ppt speaks about all the above types of nanotechnology: