PostgreSQL is an open source object-relational database management system (ORDBMS) that is used to store and retrieve data. It is designed to handle large datasets and complex queries, and is used by many organizations for mission-critical applications.
For example, PostgreSQL can be used to store customer information for an e-commerce website, store financial records for a bank, or store medical records for a hospital. PostgreSQL provides a robust set of features that make it well-suited for these types of applications. It also provides scalability, reliability, and high performance.