The main purpose of the USB-C to Lightning cable is to connect Apple devices (such as iphones, ipads, etc.) with devices that support the USB-C interface for data transfer and charging. It allows users to transfer data to and from Apple devices by connecting to a computer, charger, or other USB-C device, while also providing fast and efficient charging for Apple devices. This allows users to easily back up files, photos, audio, video, etc., as well as charge their devices when needed.