In the context of databases, “cloud” refers to storing your data on machines that belong to a third-party cloud provider. This is more cost efficient than on-prem storage, as it eliminates the need for a company to maintain its own machines, and typically increases the availability and scalability of the company’s services. This is because with cloud storage, data is stored across many smaller computers inside a data warehouse and across data warehouses (when storing data on-prem, it’s usually stored in a single massive computer or mainframe).