A teletype, also known as a TTY (teletypewriter), is an early communication device that let people send typed messages over long distances using telephone or telegraph lines.
Before computers and email, teletypes were used a bit like a combination of a typewriter and a text-only phone:
- You’d type your message on a keyboard.
- The machine would encode your keystrokes into electrical signals.
- Those signals would travel over a wire (telephone or telegraph line).
- On the other end, another teletype machine would print the message on paper.
Today, you’ll still see TTY used in the context of accessibility for people who are deaf or hard of hearing. In that setting, a TTY is a device that lets users type messages over a phone line instead of speaking and listening, making real-time text conversations possible.
