PostgreSQL also known as Postgres, is a free and open-source relational database management system (RDBMS) with an emphasis on extensibility and SQL compliance.
PostgreSQL includes transactions with ACID properties, automatically updatable views, materialized views, triggers, foreign keys, and stored procedures.
It is designed to handle a wide variety of workloads, from single machines with multiple concurrent users to data warehouses or web services.
PostgreSQL manages concurrency through Multiversion Concurrency Control (MVCC), which gives each transaction a “snapshot” of the database, allowing changes to be made without affecting other transactions.
PostgreSQL provides an asynchronous messaging system that is accessed through NOTIFY, LISTEN, and UNLISTEN commands.
PostgreSQL includes built-in support for regular B-tree and hash table indexes, and four index access methods: generalized search tree (GIST), generalized inverse index (GIN), space-partitioned GIST (SP-GIST) and block range index ( Brin).
Official website: https://www.postgresql.org/