Fax

fax, in full facsimile, also called telefax, in telecommunications, the transmission and reproduction of documents by wire or radio wave. Common fax machines are designed to scan printed textual and graphic material and then transmit the information through the telephone network to similar machines, where facsimiles are reproduced close to the form of the original documents. Fax machines, because of their low cost and their reliability, speed, and simplicity of operation, revolutionized business and personal correspondence. They virtually replaced telegraphic services, and they also present an alternative to government-run postal services and private couriers.