PostgreSQL is a robust, next-generation, Object-Relational DBMS (ORDBMS), 
derived from the Berkeley Postgres database management system.  While 
PostgreSQL retains the powerful object-relational data model, rich data types 
and easy extensibility of Postgres, it replaces the PostQuel query language 
with an extended subset of SQL.

The original Postgres code was the effort of many graduate students, 
undergraduate students, and staff programmers working under the direction of 
Professor Michael Stonebraker at the University of California, Berkeley. In 
1995, Andrew Yu and Jolly Chen took on the task of converting the DBMS query 
language to SQL and created a new database system which came to known as 
Postgres95. Many others contributed to the porting, testing, debugging and 
enhancement of the Postgres95 code. As the code improved, and 1995 faded into 
memory, PostgreSQL was born.

PostgreSQL development is presently being performed by a team of Internet 
developers who are now responsible for all current and future development. The 
development team coordinator is Marc G. Fournier (scrappy@PostgreSQL.ORG). 
Support is available from the PostgreSQL developer/user community through the 
support mailing list (questions@PostgreSQL.ORG).

PostgreSQL is free and the complete source is available.