Touch-tone phones are a type of telephone that use a keypad with buttons to dial numbers. Each button emits a specific tone when pressed, allowing the phone system to recognize the number being dialed. This technology replaced rotary dial phones, making it faster and easier to make calls. Introduced in the 1960s, touch-tone phones became popular for their convenience and efficiency. They are commonly used in homes and businesses, and their design paved the way for modern smartphones. Today, touch-tone technology is still utilized in various applications, including automated phone systems and interactive voice response systems.