In the field of telecommunications, the word fax (facsimile) refers to the act of transmitting copies over a telephone network. This system enjoys a distinct advantage because the transfer is immediate. This machine consists of a modem and an image scanner. Sometimes, the equipment is equipped with printers and photo-copiers. Although these machines have existed since the last century, they began to gain popularity in the last two decades due to their economic affordability.

Digital fax machines gained popularity in Japan. In recent years, the internet has made inroads into the field of telecommunications but the machines have continued to remain a popular choice, even in the corporate world,for the transfer of documents. Fax servers have replaced the old fax machines. These can receive faxes and transmit the information over the internet to the user. There are two kinds of fax machines.

The analog machines used earlier, are no longer in vogue. Digital machines have replaced them. The digital machines have two groups, Group three and group four. The machines are classified on the basis of the time they take to transmit a document. There are also different classes of this machines and different transmission rates. These machines use a variety of modulation methods to transmit data. It use two different methods of compression to reduce the amount of data that needs to be transmitted between two machines. These methods are Modified Huffmann and Modified Read. In the Modified Huffmann method each word is scanned and compressed independently. The amount of white space is also reduced considerably. This helps in minimising the time taken for transmission. The Modified Read Method uses a slightly different method of compression.

The first line is scanned using the MH method. The second line is scanned and the differences are determined. These differences are transmitted after a process of encoding. This method pre-supposes that these differences are minimal. The Matsushita White Line Skip is another method of compression but it can be used only on Panasonic machines.

Most of the machines that are used currently belong to the Group Three. Documents are scanned in black and white. Thermal printers that were hitherto used have given way to a generation of this machines. Thermal transfer printers,laser printers and ink-jet printers are some of these machines. Thermal fax papers, however, do not possess legal validity as the ink used in these papers is not indelible.

Fax machines come now in compact sizes and are very portable. They are also all-in-one machines that lend themselves to official and personal use, that can print, scan and fax. These machines have become versatile and they are invaluable in any corporate setting or a business house.