PostgreSQL is a standards-compliant object-relational database system with over 35 years of active development. It offers full ACID compliance, complex queries, foreign keys, triggers, updatable views, transactional integrity, and multiversion concurrency control (MVCC).
PostgreSQL runs on all major operating systems and supports a wide range of data types, indexing methods, and procedural languages. Its extensibility model allows users to define custom functions, operators, index types, and even new data types.