The printed copy is calls hard copy Fax is short form of facsimile machine. It is a device used to send/receive ima i over a telephone line. It works by digitizing an image dividing it into a grid of dou. Each dot is either on or off, depending on whether it is black or white Electronically, each dot is represented by a bit that has a value either 0 (off or l (on). In this way, the fax machine translates an image into a series of zeros and ones (called a bit map) th t can be transmitted like normal computer data. On the receiving side, a fax machine reads the incoming data, translates the zeros and ones back into dots, and reprints the picture. 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 in images on paper. But fax machines revolution came in 1983 with adoption of standard protocol for sending faxes. Now, fax machines are common in offices of all sizes They provide an inexpensive, fast, and reliable method for transmitting certificates and handwritten notes etc. 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. Some printers on fax manchines are thermal, which means they require special kind of paper.