The current PostgreSQL server version format is Major.Maintenance, from 10 onward. The first release was 10.0, and subsequent maintenance releases will be 10.1, 10.2, 10.3, and so on.
Prior to release 10, PostgreSQL used a three-part numbering series, meaning that the feature set and compatibility related to the Major.Minor release level. What this means is that version 9.4 contains more additional features and compatibility changes when compared to version 9.3. There is also a separate version of the manual, so if something doesn't work exactly the way you think it should, you must consult the correct version of the manual. Maintenance software releases were identified by the full three-part numbering scheme. Version 9.4.0 was the initial release of 9.4, and version 9.4.1 was a later maintenance release.
The release support policy for PostgreSQL is available at http://www.postgresql.org/support/versioning/. This article explains that each release will be supported for a period of five years. Since we release one major version per year, this means five major releases.
All releases, up to and including 9.2, were de-supported in September 2017. So, by the time you're reading this book, only the PostgreSQL 9.3 and higher versions will be supported. The earlier versions are still robust, though many performance and enterprise features are missing from those releases. The later de-support dates are as follows:
| Version | Last supported date |
| PostgreSQL 9.3 | September 2018 |
| PostgreSQL 9.4 | December 2019 |
| PostgreSQL 9.5 | January 2021 |
| PostgreSQL 9.6 | September 2021 |
| PostgreSQL 10 | September 2022 |