Cloud storage is the delivery of on-demand data storage services over the Internet, enabling organizations to store, manage, and access data without maintaining physical storage infrastructure. Cloud providers like AWS, Azure, and Google Cloud offer multiple storage types (object, block, file) optimized for different workloads, with pricing models based on storage capacity, access frequency, and data transfer. The key mental model: cloud storage is not one thing — it's a spectrum of storage services ranging from ultra-fast block storage for databases to ultra-cheap archival storage for compliance data, each with distinct performance characteristics, durability guarantees, and cost structures. Understanding when to use object storage vs. block vs. file storage, how to apply lifecycle policies to automatically transition data between storage classes, and how to implement proper security and redundancy configurations are essential skills for optimizing both cost and performance in cloud environments.