PostgreSQL is an advanced, open source object-relational database system with over 35 years of active development that has earned it a strong reputation for reliability, feature robustness, and performance. It supports both SQL (relational) and JSON (non-relational) querying , and is known for its extensibility, allowing users to add custom functions and data types. It is used by a wide range of organizations, from small businesses to large enterprises, for a variety of applications.