I have been reading up on entity component game engine architecture a lot lately. Essentially, an entity component system uses composition to create objects and throws away old-school inheritance style programming. This is because game objects feature a lot of complex functionality that can create inheritance chain problems. I understand the concept and it makes a lot of sense, but there are very few nuts-and-bolts breakdowns of how to implement an entity component system.
Luckily, Richard Lord has come to the rescue with Ash. It’s an Actionscript3 entity component game engine. He also wrote an extremely detailed blog post outlining the difference between an inheritance-based design and an entity component design, with a ton of code snippets so you can see the implementation details.
Please note that Ash is just one variation of an entity component system. There are other ways to do it, but this is the best explanation of entity component systems that I’ve found.