# What is PostgreSQL
PostgreSQL is an object-relational database management system (ORDBMS) based on POSTGRES, Version 4.2, developed at the University of California at Berkeley Computer Science Department.
Today, PostgreSQL is an open-source descendant of this original Berkeley code, with over 30 years of active development that has earned it a strong reputation for reliability, feature robustness, and performance.
It supports most of the SQL standard and offers many modern features, such as:
- execution of complex queries
- primary keys, foreign keys and referential integrity constraints
- updatable views
- transactional integrity
- multiversion concurrency control
Also, PostgreSQL can be extended by the user in many ways, for example by adding these new features:
- user defined data types
- aggregate functions
- index methods
- procedural languages
And because of the liberal license agreement, PostgreSQL can be used, modified, and distributed by anyone free of charge for any purpose, be it private, commercial, or academic.
One of the vendors using PostgreSQL is Amazon with its cloud-based Amazon Web Services RDS database (RDS).
Amazon RDS makes it easy to set up, operate, and scale PostgreSQL deployments in the cloud environment. With Amazon RDS, you can deploy scalable PostgreSQL deployments in minutes with cost-efficient and resizable hardware capacity. Amazon RDS manages complex and time-consuming administrative tasks such as PostgreSQL software installation and upgrades; storage management; replication for high availability and read throughput; and backups for disaster recovery.
Amazon RDS for PostgreSQL gives you access to the capabilities of the familiar PostgreSQL database engine. This means that the code, applications, and tools you already use today with your existing databases can be used with Amazon RDS. Amazon RDS supports PostgreSQL version 11, which includes a number of enhancements to performance, robustness, transaction management, query parallelism, and more.