Definition: fax

(FACSimile) Originally called "telecopying," it is the communication of a printed page between remote locations. Fax machines scan a paper form and transmit a coded image over the telephone or the Internet. The receiving machine prints a copy (facsimile) of the original. A fax machine is a scanner, printer and fax modem.

Invented in the mid-1800s, faxes were sent via telegraph, radio and satellite until the 1960s when Xerox fax machines employed telephone lines.

Group 1, 2, 3 and 4
Fax standards were developed starting in 1968 and are classified by Groups. Groups 1 and 2, used until the late 1980s, transmitted a page in six and three minutes respectively. Group 3 transmits at less than one minute per page and uses data compression at 9,600 bps. The Group 3 speed increase led to the extraordinary rise in usage in the late 1980s. Group 3 resolutions are 203x98 dpi in standard mode, 203x196 in fine mode and 203x392 in super fine mode.

Group 3 is the common standard, but Group 4 machines can transmit a page in just a few seconds and provide up to 400x400 resolution. Group 4 requires 56 to 64 Kbps bandwidth and needs ISDN, Switched 56 circuits or DSL lines.

Still Relevant in the 2020s
Although there has been a decline in usage, faxing has not by any means gone away. There is a huge user base of fax machines, and faxes enable signatures to be transmitted securely. They provide proof of message receipt, and the legal system is thoroughly familiar with them. Fax capability is available in millions of multifunction printers, and faxes can be sent from any computing device. In addition, Asian alphabets are easier to write by hand, making faxes very convenient. See fax/modem, Internet faxing and email.

The Printing Telegraph

The first fax-like machine was invented by Scottish inventor Alexander Bain in the mid-1800s, and this version was built by Siemens & Halske in Russia around 1900. Able to transmit about 40 words per minute, 28 piano keys were turned into English and Cyrillic alphabets. (Image courtesy of the Ambanmba collection.)

A Different Kind of Fax Machine

This earlier portable from Reflection Technology weighed eight ounces, worked with most cellphones and stored 25 fax pages. Its internal display simulated a 12" monitor, and a lever and buttons selected menu options. (Image courtesy of Reflection Technology, Inc.)