PHP Design Patterns Blog Posts
The Observer design pattern is very common, and luckily is a very easy concept to understand. Here it is explained!
The front controller is a simple to understand design pattern where you have a main controller that handles every request for a website. It is a commonly used design pattern for many MVC based web applications.
An explanation of the S.O.L.I.D. principles, and how to use them in your PHP scripts.
The decorator pattern explained, with a full and easy to understand example (using PHP).
The Chain of Responsibility design pattern is gaining in popularity, since being part of the PSR-15 standard (HTTP Request Middleware). Here is a quick overview of it. It let's you chain actions, and often gives them the ability to stop the chain.