Fax
A fax (short for telefacsimile) is a document, sent via a telephone network, usually from one fax machine to another fax machine. It may also be sent to/from a computer or to/from a cellular/mobile telephone.
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It is virtually a 'photocopy' of the original document.
- A fax is a instantaneous and relatively low-cost form of transmission.
A few faxed pages can be sent per minute. - Faxes are usually sent in black-and-white, but may be sent in colour depending on the available technology.
Image credit - Formal faxes, and those sent to fax machines with many recipients, often have a covering page or section, which is addressed to the fax recipient. This is similar to the envelope of a letter and condenses the necessary information.
Image credit - On the negative side, faxed documents may lack privacy, as they are open for anyone to read.
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Although a fax is sent electronically rather than by mail, it is a document, and therefore the rules for formatting and register to depend on what is appropriate for that particular type of document.