the term nano is derived from the Greek word "nanos" which means dwarf. nanometer is a unit of spatial measurement that is 10^-9 meter, or one billionth of a meter. One nanometer is the four to ten times the diameter of an atom; About 20 millionths the diameter of human hair. A cube of 2.5 nm on a side would contain about a thousand atoms. The smallest feature in an integrated circuit of today is 250 nm on a side, and contains one million atoms in a layer of atomic height. There are as many nanometers in an inch as there are inches in 400 miles.
All materials are composed of grains, which in turn comprise many atoms. These grains are usually invisible to the naked eye, depending on their size. Conventional materials have grains varying in size anywhere from 100's of microns (�m) to millimeters (mm). A micron (�m) is a micrometer or a millionth (10-6) of a meter. An average human hair is about 100 �m in diameter. A nanometer (nm) is even smaller a dimension than a �m, and is a billionth (10-9) of a meter. A nanocrystalline material has grains on the order of < 100 nm. The average size of an atom is on the order of 1 to 2 angstroms (�) in radius. 1 nanometer comprises 10 �, and hence in one nm, there may be few atoms, depending on the atomic radii.
Many scientific and technological advances have been made recently that depend on the properties of materials at a very very small scale. Such technological advances are known as �nanotechnology�.
Nanotechnology is the study and use of materials, devices, and systems on the scale of a nanometer. Nanotechnology which aims at the ideal miniaturization of devices and machines down to atomic and molecular sizes has been a recent hot topic as a promising high-technology for the forthcoming century. One of the basic principles of nanotechnology is positional control. At the molecular scale, the idea of holding and positioning molecules is new and almost shocking. Eugene Wong, a National Science Foundation assistant director, suggested that using atom-by-atom manipulation scientists could change the properties of a material without altering its chemical composition. Scientists and engineers typically have approached the synthesis and fabrication of high surface area nanostructures from one of two directions. The "bottom up" approach in which the nanostructures are built up from individual atoms or molecules. This is the basis of most "cluster science" as well as crystal materials synthesis, usually via chemical means. Both high surface area particles and micro- and mesoporous crystalline materials with high void volume (pore volume) are included in this "bottom up" approach. The "top down" approach in which nanostructures are generated by breaking up bulk materials. This is the basis for techniques such as mechanical milling, lithography, precision engineering, and similar techniques that are commonly used to fabricate nanoscale materials, which in turn can be used directly or as building blocks for macroscopic structures. However, for new nanotechnology products, still there are many challenges to be solved, and nano manipulation is one of the important challenges at the nano world.
Nanotechnology should let us make almost every manufactured product faster, lighter, stronger, smarter, safer and cleaner.
Improved transportation: Nanotechnology will dramatically reduce the costs and increase the capabilities of space ships and space flight.
Atom computers : With Nanotechnology, we should be able to build mass storage devices that can store more than a hundred billion billion bytes in a volume the size of a sugar cube and massively parallel computers of the same size that can deliver a billion billion instructions per second.
Solar energy : Nanotechnology will cut costs both of the solar cells and the equipment needed to deploy them, making solar power economical.
Medical uses: If we had surgical tools that were molecular both in their size and precision, we could develop a medical technology that for the first time would let us directly heal the injuries at the molecular and cellular level that are the root causes of disease and ill health.
