Azure Cosmos DB is a globally distributed, multi-model database service offered by Microsoft that is designed to provide high availability, scalability, and low-latency access to data for mission-critical applications. It is a NoSQL database, which means it can handle unstructured and semi-structured data types. Some key features of Azure Cosmos DB include:

• Multi-model: Azure Cosmos DB supports multiple data models, including document, key-value, graph, and column-family data models.

• Global distribution: Azure Cosmos DB databases can be configured to be available in any of the Microsoft Azure regions, letting application developers place their data closer to where their users are. Each containers data gets transparently replicated across all configured regions, and adding or removing regions is performed without any downtime or impact on performance.

• Low latency: Azure Cosmos DB offers single-digit millisecond response times, automatic and instant scalability, and guaranteed speed at any scale.

• SLA-backed availability: Business continuity is assured with SLA-backed availability and enterprise-grade security.

Azure Cosmos DB can be used with a variety of programming languages, including Java, Node.js, Python, .NET, and JavaScript. It is used by Microsoft in many of its own apps, including Microsoft Office, Skype, Active Directory, Xbox, and MSN. Azure Cosmos DB is a cloud-based NoSQL database offered as a PaaS (Platform as a Service) from Microsoft Azure.