From the 1970s onward, the rotary dial was gradually supplanted by DTMF (dual-tone multi-frequency) push-button dialing, first introduced to the public at the 1962 World's Fair under the trade name "Touch-Tone". Touch-tone technology primarily used a keypad in the form of a rectangular array of push-buttons. Although no longer in common use, the rotary dial's legacy remains in the verb "to dial (a telephone number)".