The term "Nanotechnology" was coined in 1974 by Norio Taniguichi of Tokyo Science University to describe semiconductor processes such as thin-film deposition that deal with control on the order of nanometers. His definition still stands as the basic statement today: "Nano-technology mainly consists of the processing of separation, consolidation, and deformation of materials by one atom or one molecule."
So what exactly is nanotechnology? One of the problems facing this technology is the confusion about how to define nanotechnology. Most revolve around the study and control of phenomena and materials at length scales below 100 nm and quite often they make a comparison with a human hair, which is about 80,000 nm wide.
Nanotechnology refers to controlling, building, and restructuring materials and devices on the scale of atoms and molecules.
Also, Nanotechnology refers broadly to a field of applied science and technology whose unifying theme is the control of matter on the molecular level in scales smaller than 1 micrometre, normally 1 to 100 nanometers, and the fabrication of devices within that size range.
It is also the design, characterization, production, and application of structures, devices, and systems by controlled manipulation of size and shape at the nanometer scale (atomic, molecular, and macromolecular scale) that produces structures, devices, and systems with at least one novel/superior characteristic or property.
Some definitions include a reference to molecular nanotechnology systems and devices and 'purists' argue that any definition needs to include a reference to "functional systems".
Another important criteria for the definition is the requirement that the nano-structure is man-made, i.e. a synthetically produced nanoparticle or nanomaterial. Otherwise you would have to include every naturally formed biomolecule and material particle, in effect redefining much of chemistry and molecular biology as 'nanotech.
The U.S. National Nanotechnology Initiative (NNI) provides the following definition:
... the understanding and control of matter at dimensions between approximately 1 and 100 nanometers, where unique phenomena enable novel nanotechnology applications. Encompassing nanoscale science, engineering, and technology, nanotechnology involves imaging, measuring, modeling, and manipulating matter at this length scale.
Nanotechnology can be defined as methods that create materials or structures with designed features in the 1–100nm size range (Niemeyer, 2002; Whitesides et al., 1991.From: Advances in Applied Microbiology, 2012)