Azure Cosmos DB is Microsoft's globally distributed, multi-model database. Azure Cosmos DB was built from the ground up with global distribution and horizontal scale at its core. It offers turnkey global distribution across any number of Azure regions by transparently scaling and replicating your data wherever your users are. You can elastically scale throughput and storage worldwide, and pay only for the throughput and storage you need. Azure Cosmos DB guarantees single-digit-millisecond latencies at the 99th percentile anywhere in the world, offers multiple well-defined consistency models to fine-tune performance, and guarantees high availability with multi-homing capabilities - all backed by industry leading comprehensive service level agreements (SLAs).
The currency of Azure Cosmos DB is the Request Unit (RU). With RUs, you do not need to reserve read/write capacities or provision CPU, memory, and IOPS.