Azure Cosmos DB is Microsoft’s globally distributed, multi-model database service. Cosmos DB is horizontally scalable, globally distributed, fully managed, low latency, multi-model, multi query-API database for managing data at large scale. Cosmos DB is a PaaS (Platform as a Service) offering from Microsoft Azure and is a cloud-based NoSQL database.
Please refer to Microsoft documentation for more details :
https://docs.microsoft.com/en-us/azure/cosmos-db/introduction
Benefits of Cosmos DB :
Globally Distributed
With Azure Cosmos DB, your data can be replicated globally by adding Azure regions with just one click.
Elastic scalability of throughput and storage
Designed with transparent horizontal partitioning and multi-master replication, Cosmos DB offers unprecedented elastic scalability for your writes and reads, all across the globe.
Guaranteed low latency at 99th percentile
Using Cosmos DB, you can build highly responsive, planet scale applications. With its novel multi-master replication protocol and latch-free and write-optimized database engine, Cosmos DB guarantees less than 10-ms latencies for both, reads (indexed) and writes at the 99th percentile, all around the world. This capability enables sustained ingestion of data and blazing-fast queries for highly responsive apps.
Schema-Agnostic Indexing
Cosmos DB’s database engine is schema agnostic, and this enables automatic indexing of the data. Cosmos DB automatically indexes all the data without requiring schema and index management.
Multi-Model
Cosmos DB is a multi-model database, i.e., it can be used for storing data in Key-value Pair, Document-based, Graph-based, Column Family-based databases. Irrespective of which model you choose, data persistence, global distribution, provisioning throughput, horizontal partitioning and automatic indexing capabilities are the same.
Multi-API and Multi-Language Support
Microsoft has released SDKs for multiple programming languages including Java, .NET, Python, Node.js, JavaScript, etc. Cosmos DB has Multi API support, i.e., SQL API, Cosmos DB Table API, MongoDB API, Graph API, Cassandra API, and Gremlin API.
Multi-Consistency Support
Cosmos DB supports 5 consistency levels.
Indexes Data Automatically
Cosmos DB indexes data automatically on ALL fields in all documents by default without the need for secondary indexes, but you can still create custom indexes. Azure’s automatic indexing capability indexes every property of every record without having to define schemas and indices upfront. This capability works across every data model.
High Availability
Cosmos DB provides 99.999% availability for both reads and writes for multi-region accounts with multi-region writes. Cosmos DB provides 99.99% availability for both reads and writes for single-region accounts. Cosmos DB automatically fails over in case of disaster.
The following figure lists Azure API’s and their specialized entity.
Get started with creating Azure Cosmos DB with the following API’s.
Tweak 