A key to understanding nanotechnology is realizing precisely what it is and what it isn't. Here we are talking about research and development in the length scale of .1 nanometers to 100 nanometers to create unique structures, devices, and systems. In many instances the actual structures, devices, and systems will be much larger, but they will be classified as nanotechnology due to the fact that they will either be created at the nanoscale or nanotechnology will enable them to perform new and/or improved functions.
The term "nanotechnology" has evolved over the years to mean "anything smaller than microtechnology," such as nano powders, and other things that are nanoscale in size, but not referring to mechanisms that have been purposefully built from nanoscale components. This evolved version of the term is more properly labeled "nanoscale bulk technology," while the original meaning is now more properly labeled "molecular nanotechnology" (MNT), or "nanoscale engineering," or "molecular mechanics," or "molecular machine systems," or "molecular manufacturing."
At the most basic technical level, MNT is building with intent and design, and molecule by molecule, these two things: 1) incredibly advanced and extremely capable nano-scale and micro-scale machines and computers, and 2) ordinary size objects, using other incredibly small machines called assemblers or fabricators (found inside nanofactories). In a nutshell, by taking advantage of quantum-level properties, MNT allows for unprecedented control of the material world, at the nanoscale, providing the means by which systems and materials can be built with exacting specifications and characteristics.
MNT represents the state of the art in advances in biology, chemistry, physics, engineering, computer science and mathematics. The major research objectives in MNT are the design, modeling, and fabrication of molecular machines and molecular devices. The emergence of MNT - both infant and mature - has numerous social, legal, cultural, ethical, religious, philosophical and political implications.
At the most basic social level, MNT is going to be responsible for massive changes in the way we live, the way we interact with one another and our environment, and the things we are capable of doing.