PostgreSQL is a powerful open-source relational database management system that supports SQL (Structured Query Language). It offers several key features such as constraints, data types, foreign keys, joins, normalization, partitioning, primary keys, relationships, schemas, stored procedures, tables, transactions, triggers, and views. These features help in managing and organizing data efficiently while ensuring its accuracy and reliability. PostgreSQL is widely used for various applications due to its robustness, scalability, and flexibility.