A recent post on the Developer Tutorials blog takes a look at a fundamental part of several of the PHP (and other language) frameworks out there - the Object Relational Mapping (ORM) layer for database access.

Instead of direct database access, an ORM layer in a PHP framework can make "objects" stored in a database behave like actual objects from a programming perspective - for example, creating a new "car" stored in the database could involve a call to $car->new(). By abstracting actual database access, web development can be more productive and result in more reliable applications. Here's a quick intro to ORM in PHP.

They talk about ORM's role in how applications interface with data (abstracted out to objects) and some examples of it in current frameworks - CakePHP and Symfony.