What is PostgreSQL?

PostgreSQL is a free, open-source object-relational database management system (ORDBMS). That phrase is worth unpacking, because it explains a lot about why PostgreSQL behaves the way it does and why it has such a loyal following among developers and database administrators.

Origins at UC Berkeley

PostgreSQL traces its roots to 1986, when Professor Michael Stonebraker began a research project at the University of California, Berkeley called POSTGRES — short for “post-Ingres,” a follow-up to an earlier database project also led by Stonebraker. The goal of POSTGRES was to explore ideas that most databases of the era did not support well: complex data types, rules, and the ability for users to define their own types and behaviors rather than being limited to a fixed, rigid schema.

In the early 1990s, the project added a SQL query language interpreter and was renamed Postgres95, and then finally PostgreSQL in 1996 to reflect its support for standard SQL. Development has continued in the open ever since, with a new major release shipping every year.

What “object-relational” actually means

A purely relational database stores data strictly as rows and columns using a small set of primitive types (numbers, text, dates). An object-relational database keeps that same relational foundation — tables, rows, SQL, transactions — but adds concepts borrowed from object-oriented programming on top of it:

Rich, extensible data types — arrays, JSON/JSONB documents, geometric types, IP address ranges, and more, alongside the usual numbers and text
Table inheritance — one table can inherit the columns of another, useful for certain partitioning and modeling patterns
User-defined types and functions — you can define entirely new data types and the operators/functions that work with them
Custom operators and index types — advanced users can teach PostgreSQL new ways to store and search their data

This is the single biggest thing that sets PostgreSQL apart from a traditional relational database: it was designed from day one to be extended rather than treated as a closed box.

Standards compliance and extensibility

PostgreSQL has a strong reputation for closely following the SQL standard, which makes behavior predictable and queries portable across systems. At the same time, its extension system lets you add entirely new capabilities without waiting on the core project — popular extensions include PostGIS (geospatial data), pg_stat_statements (query performance monitoring), and pgcrypto (cryptographic functions).

Enabling an extension

SQL

-- Extensions are opt-in per database
CREATE EXTENSION IF NOT EXISTS pgcrypto;

Community and license

PostgreSQL is developed by a large, global community of volunteers and companies, coordinated in the open with no single corporation controlling its direction. It is released under the PostgreSQL License, a permissive, MIT-style license that allows free use, modification, and distribution — including in proprietary commercial products — with minimal restrictions.

Aspect	Detail
First released	1996 (as "PostgreSQL"), project began 1986
Type	Object-relational database management system
License	PostgreSQL License (permissive, similar to MIT/BSD)
Governance	Open community, no single corporate owner
Release cadence	One major version per year, with minor patch releases

Why this history matters

Understanding that PostgreSQL was built to be extensible — not just to store rows and columns — explains why features like JSONB, arrays, and custom types feel so natural in Postgres rather than bolted on as an afterthought.