A modern office fax machine scans a page to make an electronic representation of its text or graphics, compresses the data to save transmission time, and transmits it to another fax machine (or computer emulating a fax machine). The receiving machine decrypts the signal and uses a printer (usually built in) to make a facsimile of the original page. Because of the adoption of Group 3 digital standards in 1980 by the CCITT (International Telegraph and Telephone Consultative Committee), facsimile devices have become extremely prevalent in offices. These machines work over the public telephone network; they use digital modems and transmit at data rates up to 9600 bits per second. Images are produced with a resolution of 200 dots per inch. Personal computers can emulate Group 3 facsimile machines if they are equipped with a fax modem, printer, and appropriate software. Facsimile machines that produce higher-resolution images or color and gray-scale images are also available.
A facsimile (From Latin fac simile, "make like") is a copy or reproduction of an old book, manuscript, map, art print or other item of historical value that is as true-to-the-original source as possible using, normally, some form of photographic technique. They differ from other forms of reproduction by attempting to replicate the source as accurately as possible in terms of scale, colour, condition, and other material qualities. For books and manuscripts, this also entails a complete copy of all pages; hence an incomplete copy is known as a "partial facsimile". Facsimiles are used, for example, by scholars to research a source that they do not have access to otherwise and by museums and archives for museum and media preservation. Many are sold commercially.
Facsimiles play an important role in the study of history, palaeography and other fields where ready-access to an otherwise unavailable original document is essential for close examination. The copy of Edgar Allan Poe's original manuscript for "The Murders in the Rue Morgue" allows a wider availability of such resources and for researchers to see corrections and changes in the writer's autograph hand in a quality that rivals the original.
Facsimiles are best suited to printed or hand-written documents, and not to items such as three dimensional objects or oil paintings with unique surface texture. Reproductions of those latter objects are often referred to as replicas.