A teleprinter (teletypewriter, Teletype or TTY for TeleTYpe/TeleTYpewriter) is a now largely obsolete electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communications channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the transmission medium. They could also serve as a command line user interface to early mainframes and minicomputers, sending typed data to the computer with or without printed output, and printing the response from the computer. Teleprinters are still widely used in the Aviation industry.
