The Github repository domnikl/DesignPatternsPHP has a list of design patterns and their implementation in PHP.
It shows the UML diagram for the pattern and explains the purpose of the pattern.
To create series of related or dependent objects without specifying their concrete classes. Usually the created classes all implement the same interface. The client of the abstract factory does not care about how these objects are created, he just knows how they go together.
Some examples are the Composite, the FluentInterface, the Observer, the Repository or the famous Singleton anti-pattern.