Nanocomputer refers to a computer smaller than the microcomputer, which is smaller than the minicomputer. Microelectronic components that are at the core of all modern electronic devices employ semiconductor transistors. 

Nanocomputing describes computing that uses extremely small, or nanoscale, devices (one nanometer [nm] is one billionth of a meter). In 2001, state-of-the-art electronic devices could be as small as about 100 nm, which is about the same size as a virus. The integrated circuits (IC) industry, however, looks to the future to determine the smallest electronic devices possible within the limits of computing technology.

Until the mid-1990s, the term "nanoscale" generally denoted circuit features smaller than 100 nm.As the IC industry started to build commercial devices at such size scales since the beginning of the 2000s, the term "nanocomputing" has been reserved for device features well below 50 nm to even the size of individual molecules, which are only a few nm. Scientists and engineers are only beginning to conceive new ways to approach computing using extremely small devices and individual molecules.