Once you begin to serve, and supply services to your customers, you'll inevitably find that you need to keep information about them in an archive to be accessible and modifiable at any time, should you want it. These tasks can be accomplished
with the use of a database. Many databases are available on Linux; Choosing one can be complicated, as it must be able to support a number of programming languages, standards and features. PostgreSQL, developed originally in the UC Berkeley
Computer Science Department, pioneered many of the object-relational concepts now becoming available in commercial databases. It provides SQL92/SQL3 language support, transaction integrity, and type extensibility.