1. A global content directory, comprising: a directory structure comprising a plurality of product classes organized in a hierarchy, each product class categorizing a plurality of products and defining one or more attributes of the products categorized in the product class; one or more pointers associated with each product class, each pointer identifying a seller database in which product data enabling a product transaction is stored for products associated with the product class; and a search interface operable to communicate, in response to a selection of a product class by a user of the global content directory, a search query for product data to one or more seller databases identified by the one or more pointers associated with the selected product class.