PostgreSQL is an open-source relational database management system (RDBMS) renowned for its extensibility and strict adherence to technical standards. It supports a comprehensive set of SQL language features and leverages its extensibility to accommodate custom functions and data types. Additionally, it provides transactional integrity, robust concurrency control, multi-version concurrency control (MVCC), and a diverse indexing strategy including B-tree, hash tables, GiST, SP-GiST, GIN, and BRIN indexes. PostgreSQL is also widely regarded as one of the most advanced open-source databases and is frequently utilized for large-scale and complex data processing tasks.