A staple in the modern business world, a fax machine allows documents to be transferred between people by using telephone lines. It accomplishes this by digitizing the information to be sent so that it may be transferred very long distances almost instantaneously without the need for a physical medium along the way.
The process of sending a fax machine begins with an individual submitting a paper filled with information to the machine. When this occurs, the fax machine scans the information on the paper, converting it into a format that can be used by the sending machine and the receiving machine. This format involves black and white dots, black dots recorded when information is present on that part of the paper and white dots representing blanks.
In order to create these black and white dots, fax machines use photo-diode sensor arrays. These devices contain from several hundred to a thousand tiny sensors that detect the composition of the text or images on the paper being faxed. It sees these as light and dark spaces, transferring what it sees into the fax machine "language" of white dots and black dots.
Once the information on the page to be faxed has been converted into white and black dots, the fax machine then converts those dots to a series of sounds. This is done so that the information can be sent over a phone line in a series of electronic signals that the receiving fax machine can then decode. Essentially, the fax machine on the other end of the equation reverses the process: it receives a series of sounds, decodes them into black and white dots, and uses this framework to replicate the document.
Over the years, the technology behind fax machines has improved and advanced, allowing fax machines to send documents in color, for example. In this particular situation, each fax machine would have to be able to meet the standard of being able to produce an image in color. If either one cannot, the more advanced fax machine will only send what the other is capable of decoding and printing, allowing older fax machines to work with newer ones seamlessly.
Fax machines have become integral to modern business, allowing two parties to send documents back and forth without the need for mail, which can take longer than necessary. Important documents can also be sent without the risk of losing or damaging them, which is especially important for things like birth certificates. The process of converting a document to sound and then back to a document is hard to imagine, but for some people, it is all in a day's work.