PostgreSQL is an open source object-relational database management system that can run on Linux, UNIX and Windows. It supports a wide variety of data types and includes programming interfaces for many languages. PostgreSQL offers user-defined types, inheritance rules, multi-version concurrency control and other features not found in other databases. It also generally performs faster than other databases and has a reputation for stability due to its rigorous testing process. Support is available through mailing lists and commercial support options.