Azure Cosmos DB is a globally distributed, multi-model NoSQL database service that provides guaranteed low latency, high availability, and automatic failover across multiple regions. It supports multiple data models including SQL (Document), MongoDB, Cassandra, Gremlin (Graph), and Table APIs, allowing developers to choose the best model for their use case. Cosmos DB provides features like automatic and manual failover, multi-region writes, built-in security with encryption at rest and in transit, comprehensive backup capabilities, and seamless scaling of throughput and storage.