PostgreSQL is 100 percent open source software.
PostgreSQL is freely available to use, alter, or redistribute in any way you choose. Its license is an approved open source license, very similar to the Berkeley Distribution Software (BSD) license, though only just different enough that it is now known as The PostgreSQL License (TPL).
PostgreSQL is already being used by many different application packages, so you may find it already installed on your servers. Many Linux distributions include PostgreSQL as part of the basic installation, or include it with the installation disk.
One thing to be wary of, is that the version of PostgreSQL included may not be the latest release. It will typically be the latest major release that was available when that operating system release was published. There is usually no good reason to stick to that level—there is no increased stability implied there—and later production versions are just as well supported by the various Linux distributions as the earlier versions.
If you don't have a copy yet, or you don't have the latest version, you can download the source code or binary packages for a wide variety of operating systems from http://www.postgresql.org/download/.
Installation details vary significantly from platform to platform, and there aren't any special tricks or recipes to mention. Just follow the installation guide, and away you go! We've consciously avoided describing the installation processes here to make sure we don't garble or override the information published to assist you.
If you would like to receive e-mail updates of the latest news, then you can subscribe to the PostgreSQL announce mailing list, which contains updates from all the vendors that support PostgreSQL. You'll get a few e-mails each month about new releases of core PostgreSQL, related software, conferences, and user group information. It's worth keeping in touch with these developments.
Note
For more information about the PostgreSQL announce mailing list, visit http://archives.postgresql.org/pgsql-announce/.
Many people ask questions such as "how can this be free?", "are you sure I don't have to pay someone?", or "who gives this stuff away for nothing?"
Open source applications such as PostgreSQL work on a community basis, where many contributors perform tasks that make the whole process work. For many of those people, their involvement is professional, rather a hobby, and they can do this because there is generally a great value for both contributors and their employers alike.
You might not believe it. You don't have to, because It Just Works!
Remember that PostgreSQL is more than just the core software. There is a huge range of websites offering add-ons, extensions, and tools for PostgreSQL. You'll also find an army of bloggers describing useful tricks and discoveries that will help you in your work.
Besides, there is a range of professional companies that are able to offer you help when you need it.