Teleprinters, also referred to as teletypewriters, telewriters, or simply TTYs, are electromechanical devices used for sending and receiving typed messages over telecommunication channels. The term "telex" is also used to refer to this technology. Telex machines were commonly used in the past for long-distance communication before the advent of email, fax, and other digital communication inventions. Today, teleprinters are rarely used in daily communication due to the prevalence of digital communication technologies. However, they are still used in specific industries such as aviation, military, and emergency services, where secure and reliable communication is paramount.