A rotary dial phone is a type of telephone that uses a rotating dial to input phone numbers. Users place their finger in a small hole next to the desired number and rotate the dial clockwise until it stops. After releasing the dial, it returns to its original position, sending electrical pulses to the phone line corresponding to the number dialed. Introduced in the early 20th century, rotary dial phones were common until the 1980s, when push-button phones became popular. Despite their decline, rotary phones are still appreciated for their vintage design and nostalgic value in today's technology-driven world.