iCloud is a cloud storage and computing service provided by Apple. It allows users to store their data, including photos, videos, documents, and more, on remote servers and access them from any Apple device. iCloud also offers a feature called Find My iPhone, which enables users to locate their lost or stolen iPhone. By signing in to their iCloud account on another Apple device or through the iCloud website, users can track the location of their iPhone on a map. iCloud also provides additional security features like remotely locking the device, displaying a custom message, or erasing all the data on the device. With its seamless integration with Apple devices, iCloud has become a popular choice for iPhone users to store their data and protect their devices.