The property system is a new set of APIs for Microsoft Windows Vista that provides a general way to access metadata about files and items accessible through the shell namespace. This means you can ask for the dimensions of an image, or the size of a file, without worrying about how that data is retrieved. You can see how this is useful for folder browsers that need exactly this type of functionality.
In future posts, I'll expand on the details of the property system APIs and how they can be used. For now, here's an overview: