The Azure PaaS service for the community edition of PostgreSQL, deployed as Flexible Server, with automatic backups, zone-redundant high availability, and control over maintenance windows.
In DP-900 it is one of the services for open-source databases. The Single Server option retired in March 2025. For distributed PostgreSQL with sharding, Microsoft recommends this service's elastic clusters; Cosmos DB for PostgreSQL is not recommended for new projects.
Azure Database for PostgreSQL is a concept that can show up on the exam. Check the full guide to see it in context.