Nanotechnology describes the practice of science, technology or engineering on a molecular or atomic scale. It refers to a wide application of uses across many fields of science, such as organic chemistry, physics and molecular biology, and refers to any manipulation of matter occurring on a scale of 1 to 100 nanometers.
In general terms, nanotechnology is the manipulation of matter on a very small scale, called a "nanoscale." To get an idea of how small the nanoscale is, 1 inch contains 25,400,000 nanometers, and a sheet of paper is approximately 100,000 nanometers thick.
Nanotechnology is a relatively recent phenomenon as of 2015, with microscopes powerful enough to observe material on such a small scale appearing only decades ago. These include the scanning tunneling microscope, or STM, and the atomic force microscope, also called AFM. However, the concepts of nanotechnology appeared earlier, in 1959, when the famous physicist Richard Feynman began discussing the possibility of synthesizing material through the process of molecular manipulation.
There are two main approaches to nanotechnology: the "bottom up" approach, which describes the construction of devices and materials based on the principles of molecular recognition, and the "top down" approach, by which scientists construct nano-scale objects from larger materials without using direct atomic control.