Fax (short for facsimile), sometimes called telecopying or telefax (short for telefacsimile), is the telephonic transmission of scanned printed material (both text and images), normally to a telephone number connected to a printer or other output device. The original document is scanned with a fax machine (or a telecopier), which processes the contents (text or images) as a single fixed graphic image, converting it into a bitmap, and then transmitting it through the telephone system in the form of audio-frequency tones. The receiving fax machine interprets the tones and reconstructs the image, printing a paper copy. Early systems used direct conversions of image darkness to audio tone in a continuous or analog manner. Since the 1980s, most machines transmit an audio-encoded digital representation of the page, using data compression to transmit areas that are all-white or all-black, more quickly.
Initially a niche product, fax machines became ubiquitous in offices in the 1980s and 1990s. However, they have largely been rendered obsolete by Internet-based technologies such as email and the World Wide Web, but are still used in some medical administration and law enforcement settings.
History Wire transmission
Scottish inventor Alexander Bain worked on chemical-mechanical fax-type devices and in 1846 Bain was able to reproduce graphic signs in laboratory experiments. He received British patent 9745 on May 27, 1843, for his "Electric Printing Telegraph".Bain, Alexander "Improvement in copying surfaces by electricity" U.S. patent no. 5,957 (5 December 1848). Frederick Bakewell made several improvements on Bain's design and demonstrated a telefax machine.Bakewell, Frederick Collier "Electric telegraphs" English patent no. 12,352 (filed: 2 December 1848; issued: 2 June 1849). The Pantelegraph was invented by the Italian physicist Giovanni Caselli.Caselli, Giovanni "Improved pantographic telegraph" U.S. patent no. 20,698 (June 29, 1858). He introduced the first commercial telefax service between Paris and Lyon in 1865, some 11 years before the invention of the telephone.
In 1880, English inventor Shelford Bidwell constructed the scanning phototelegraph that was the first telefax machine to scan any two-dimensional original, not requiring manual plotting or drawing.See:
An account of Henry Sutton's "telephane" was published in 1896. Around 1900, German physicist Arthur Korn invented the Bildtelegraph, widespread in continental Europe especially following a widely noticed transmission of a wanted-person photograph from Paris to London in 1908, used until the wider distribution of the radiofax. Its main competitors were the Bélinographe by Édouard Belin first, then since the 1930s the Hellschreiber, invented in 1929 by German inventor Rudolf Hell, a pioneer in mechanical image scanning and transmission.
The 1888 invention of the telautograph by Elisha Gray marked a further development in fax technology by making it possible for users to send signatures over long distances. This was used for verifying identification or ownership over long distances.Gray, Elisha "Art of telegraphy" U.S. patent no. 386,814 (filed: May 31, 1888; issued: July 31, 1888).Gray, Elisha "Telautography" U.S. patent no. 386,815 (filed: June 13, 1888; issued: July 31, 1888).
On May 19, 1924, scientists of the AT&T Corporation "by a new process of transmitting pictures by electricity" sent 15 photographs by telephone from Cleveland to New York City, such photos being suitable for newspaper reproduction. Previously, photographs had been sent over the radio using this process."Photos Sent Over Telephone Wire by Cleveland to N.Y.", The Gazette (Montreal), May 20, 1924, p.10
The Western Union "Deskfax" fax machine, announced in 1948, was a compact machine that fit comfortably on a desktop, using special spark printer paper.G. H. Ridings, A Facsimile transceiver for Pickup and Delivery of Telegrams , Western Union Technical Review, Vol. 3, No, 1 (January 1949); page 17-26.
During the 1960s and 1970s, and initially in partnership with the Canadian Press, the Royal Canadian Mounted Police utilized facsimile equipment to transmit photographs and fingerprints of criminals.
Wireless transmission
As a designer for the Radio Corporation of America (RCA), in 1924, Richard H. Ranger invented the wireless photoradiogram, or transoceanic radio facsimile, the forerunner of today's "fax" machines. A photograph of President Calvin Coolidge sent from New York to London on November 29, 1924, became the first photo picture reproduced by transoceanic radio facsimile. Commercial use of Ranger's product began two years later. Also in 1924, Herbert E. Ives of AT&T transmitted and reconstructed the first color facsimile, a natural-color photograph of silent film star Rudolph Valentino in period costume, using red, green and blue color separations.Sipley, Louis Walton (1951). A Half Century of Color. Macmillan.
Beginning in the late 1930s, the Finch Facsimile system was used to transmit a "radio newspaper" to private homes via commercial AM radio stations and ordinary radio receivers equipped with Finch's printer, which used thermal paper. Sensing a new and potentially golden opportunity, competitors soon entered the field, but the printer and special paper were expensive luxuries, AM radio transmission was very slow and vulnerable to static, and the newspaper was too small. After more than ten years of repeated attempts by Finch and others to establish such a service as a viable business, the public, apparently quite content with its cheaper and much more substantial home-delivered daily newspapers, and with conventional spoken radio bulletins to provide any "hot" news, still showed only a passing curiosity about the new medium.Schneider, John (2011). "The Newspaper of the Air: Early Experiments with Radio Facsimile". theradiohistorian.org. Retrieved 2017-05-15.
By the late 1940s, radiofax receivers were sufficiently miniaturized to be fitted beneath the dashboard of Western Union's "Telecar" telegram delivery vehicles.
In the 1960s, the United States Army transmitted the first photograph via satellite facsimile to Puerto Rico from the Deal Test Site using the Courier satellite.
Radio fax is still in limited use today for transmitting weather charts and information to ships at sea. The closely related technology of slow-scan television is still used by amateur radio operators.
Telephone transmission
In 1964, Xerox Corporation introduced (and patented) what many consider to be the first commercialized version of the modern fax machine, under the name (LDX) or Long Distance Xerography. This model was superseded two years later with a unit that would set the standard for fax machines for years to come. Up until this point facsimile machines were very expensive and hard to operate. In 1966, Xerox released the Magnafax Telecopiers, a smaller, facsimile machine. This unit was far easier to operate and could be connected to any standard telephone line. This machine was capable of transmitting a letter-sized document in about six minutes. The first sub-minute, digital fax machine was developed by Dacom, which built on digital data compression technology originally developed at Lockheed for satellite communication.The implementation of a personal computer-based digital facsimile information distribution system – Edward C. Chung, Ohio University, November 1991, page 2Fax: The Principles and Practice of Facsimile Communication, Daniel M. Costigan, Chilton Book Company, 1971, pages 112–114, 213, 239
Analog facsimile machines worked by optical scanning of a document or drawing spinning on a drum. The reflected light, varying in intensity according to the light and dark areas of the document, was focused on a photocell so that the current in a circuit varied with the amount of light. This current was used to control a tone generator (a modulator), the current determining the frequency of the tone produced. This audio tone was then transmitted using an acoustic coupler (a speaker, in this case) attached to the microphone of a common telephone handset. At the receiving end, a handset's speaker was attached to an acoustic coupler (a microphone), and a demodulator converted the varying tone into a variable current that controlled the mechanical movement of a pen or pencil to reproduce the image on a blank sheet of paper on an identical drum rotating at the same rate.
Digital transmission and height of popularity By the late 1970s, many companies around the world (especially Japanese firms) had entered the fax market, and prices for long-distance faxing in 1978 were significantly lower than they had been in 1968, both at high and low speeds. Faxes had become useful to large newspapers and multinational corporations, and some digital methods were being developed. However, the rise of the market was fairly slow. Individual manufacturers had purposefully developed incompatible transmission methods in order to prevent their customers from buying from competitors. The CCITT (later ITU-T) Recommendation T.3, defining group 2 fax machines, was the first to offer interoperability in 1976, with a speed of three minutes per page.
In 1980, the CCITT's Recommendation T.4 promised groundbreaking interoperability for digital fax machines, with transmission times of just 40 seconds per page. Accompanying this, a new wave of more compact, faster and efficient fax machines hit the market, leading to two decades of ubiquitous faxing in business contexts. Xerox continued to refine the fax machine for years after their ground-breaking first machine. In later years it would be combined with copier equipment to create the modern hybrid machines that copy, scan and fax. Some of the lesser known capabilities of the Xerox fax technologies included their Ethernet enabled Fax Services on their 8000 workstations in the early 1980s.
In 1985, Hank Magnuski, founder of GammaLink, produced the first computer fax board, called GammaFax. Such boards could provide voice telephony via Analog Expansion Bus.
In the 21st century
Although businesses usually maintain some kind of fax capability, the technology has faced increasing competition from Internet-based alternatives. In some countries, because electronic signatures on contracts are not yet recognized by law while faxed contracts with copies of signatures are, fax machines enjoy continuing support in business. In Japan, faxes were still being used extensively in 2025 for cultural reasons, including a widespread preference for handwriting over typing. They are available for sending to both domestic and international recipients from over 81% of all convenience stores nationwide. Convenience-store fax machines commonly print the slightly re-sized content of the sent fax in the electronic confirmation-slip, in A4 paper size. Use of fax machines for reporting cases during the COVID-19 pandemic has been criticised in Japan for introducing data errors and delays in reporting, slowing response efforts to contain the spread of infections and hindering the transition to remote work. The same issue has occurred in Germany and the United States. In Germany, some districts in Berlin reported zero cases for seven consecutive days. The reason was that the local health department in these districts only had fax machines and could not accurately report the number of infected individuals.
In many corporate environments, freestanding fax machines have been replaced by fax servers and other computerized systems capable of receiving and storing incoming faxes electronically, and then routing them to users on paper or via an email (which may be secured). Such systems have the advantage of reducing costs by eliminating unnecessary printouts and reducing the number of inbound analog phone lines needed by an office.