The idea of fax machines has been around since 1842, when Alexander Bain invented a machine capable of receiving signals from a telegraph wire and translating them into images on paper. In 1850, a London inventor named F. C. Blakewell received a patent for a similar machine, which he called a copying telegraph.

But while the idea of fax machines has existed since the 1800s, fax machines did not become popular until the mid 1980s. The spark igniting the fax revolution was the adoption in 1983 of a standard protocol for sending faxes at rates of 9,600 bps. The standard was created by the CCITT standards organization and is known as the Group 3 standard. Now, faxes are commonplace in offices of all sizes. They provide an inexpensive, fast, and reliable method for transmitting correspondence, contracts, résumés, handwritten notes, and illustrations.

A fax machine consists of an optical scanner for digitizing images on paper, a printer for printing incoming fax messages, and a telephone for making the connection. The optical scanner generally does not offer the same quality of resolution as stand-alone scanners. Some printers on fax machines are thermal, which means they require a special kind of paper.

All fax machines conform to the CCITT Group 3 protocol. (There is a new protocol called Group 4, but it requires ISDN lines.) The Group 3 protocol supports two classes of resolution: 203 by 98 dpi and 203 by 196 dpi. The protocol also specifies a data-compression technique and a maximum transmission speed of 9,600 bps.

Some of the features that differentiate one fax machine from another include the following:

As an alternative to stand-alone fax machines, you can also put together a fax system by purchasing separately a fax modem and an optical scanner. You may not even need the optical scanner if the documents you want to send are already in electronic form.

Sharp Electronics - Facsimile Product page
Describes Sharp's line of facsimile products.

Yahoo!'s fax machines page
Yahoo!'s directory of fax machine manufacturers and suppliers.