Touch-tone refers to a telephone system that makes musical beeping sounds when you press the number buttons. Each button produces two different tones at once, creating a unique sound that the phone system recognizes. If you've ever heard someone dialing a phone number and noticed those distinctive beep-boop sounds, you were hearing touch-tone technology.

Before touch-tone phones became common in the 1960s, people used rotary phones with a circular dial that you had to spin for each number. Touch-tone made dialing faster and easier: just press buttons instead of waiting for the dial to rotate back after each digit. The technology also enabled automated phone systems that ask you to “press 1 for English” or “press 5 to speak to a representative.”

The word describes both the technology itself and the keypads that use it. You might see instructions that say “enter your account number using your touch-tone keypad.” Even though most phones today are smartphones with touchscreens, they can still make those same touch-tone beeps when you dial, connecting modern technology to a system invented over 60 years ago.