For many applications the MOSFET is operated in only two states: with
the drain-to-source current IDS ON (gate open) or with it OFF (gate closed). The
first of these can represent a 1 and the other a 0 in the binary arithmetic on which
digital logic is based, and therefore MOSFETs can be used in digital logic circuits.
Switching between the ON and OFF states can occur at high speed, so that binary
logic data can be moved through MOSFET-based circuits very rapidly. MOSFETs
about 500 nm in length—about the same as the wavelength of yellow light—are
routinely fabricated for use in electronic devices of all kinds.