Abstract: Systems and methods to identify and associate related items are described. The system receives listing information describing a part that is offered for sale on a network-based marketplace that includes categories. The listing information includes a title and a category. The system stores the listing information in a listing according to the category. The system parses the title of the listing to identify tokens and to identify whether the tokens match a token in parts descriptors that describe parts that are associated with the first category. The system generates scores based on the tokens and the parts descriptors and may select a part type identifier based on the scores. Finally, the system registers the listing with the parts type identifier and associates listing(s) with the listing based on the parts type identifier. For example, the system may associate listings describing parts that are commonly purchased together.

Abstract: Information pertinent to an item or product may be organized (e.g., structured) as a property of the item or product. The property may be represented (e.g., stored) as property data in a data structure of the item or product. A property may have one or more properties of its own. In this manner, information pertinent to items, products, properties, or any suitable combination thereof may be structured with any level of sophistication or complexity. Accordingly, a data structure may be generated to contain one or more properties of an item or product, as well as to contain one or more properties of those properties. A “composite property” refers to such a data structure and may be indexed based on a value contained therein. The value may be used to identify the item or the product, for example, as an instance of a virtual product.