The design and manufacture of materials and devices with dimensions measured in nanometres and usually less than 100 nanometres. One nanometre is 10^–9 metre, i.e. a millionth of a millimetre. There are two approaches in nanofabrication, bottom-up nanofabrication and top-down nanofabrication. In bottom-up nanofabrication nanometre-scale devices are built up atom by atom by means of either self-assembly or atomic manipulation using scanning-probe microscopy. Top-down nanofabrication produces nanometre-scale devices from bulk materials by lithography techniques, which include photolithography, electron-beam lithography, focused ion-beam lithography, and nanoimprint lithography. The progress in nanofabrication techniques has been leading to super-high-density and super-high-speed microprocessors, memory chips, and novel nanodevices. In future quantum computers, each data bit could be stored in a single atom or a single spin. Nanofabrication also has a wide range of applications in the medical industry, clean chemistry, and the aerospace industry.