Cloud storage is a service model in which data is transmitted and stored in remote storage systems. It is maintained, managed, backed up, and made available to users worldwide (typically the internet). Users generally pay a monthly rate for their cloud data storage on a per-consumption basis. Although the per-gigabyte cost has been radically reduced, cloud storage providers have added operating costs that can make the technology significantly more expensive to use. The security of cloud storage services continues to be a concern for users. Service providers have tried to alleviate these concerns by enhancing their security capabilities by incorporating data encryption, multi-factor authentication, and improved physical security into their services.