Coin-operated devices are machines that require users to insert coins to function. Common examples include vending machines, arcade games, and laundry machines. These devices are designed to provide a service or product in exchange for a small fee, making them convenient for users who need quick access to items or entertainment. The mechanism behind coin-operated devices typically includes a coin slot, a sensor to detect the inserted coin, and a system that activates the machine once the correct amount is received. This setup allows for easy transactions without the need for cashiers or staff, streamlining the user experience.