Fax machines are used to send and receive documents that are transmitted as a stream of audio data over a telephone line. The sending machine scans a hard-copy document to create a facsimile (fax), which the receiving machine then prints. Typically, the printing mechanism is a laser or ink jet; however, some older fax machines use thermal paper. When selecting products, buyers should consider the speed of transmission. Fax machine features include scanners, email, and color printing.