10. The method as recited in claim 6 , further comprising: determining that the user has selected the second item via a site or an application associated with a service provider; parsing the explicit associative relationships between the second item and the items to determine that the first item or the first category of items are related to the second item; and dynamically recommending at least one of the first item or the first category of items to the user via the site or the application.
6. A method comprising: under control of one or more processors: determining a plurality of explicit associative relationships that include words or phrases that define a plurality of different types of relationships between at least one of (i) items of a catalog of items, or al categories of the items, wherein the plurality of explicit associative relationships are different than a plurality of hierarchical relationships between at least one of the items or the categories of the items, and wherein the plurality of different types of relationships include at least one of: an optional accessory relationship that indicates that at least one of a first item or a first category of items is both suggested for use with a second item and not necessary for using the second item, a necessary accessory relationship that indicates that at least one of the first item or the first category of items is necessary for using the second item, or a consumable accessory relationship that indicates that at least one of the first item or the first category of items is consumed during use in conjunction with the second item; and assigning the plurality of explicit associative relationships to at least one of the items or the categories of items, the plurality of explicit associative relationships being utilized to recommend, to one or more users, at least one of the first item or the first category of items based on the second item having been selected by a user of the one or more users; parsing the plurality of explicit associative relationships assigned to the second item to identify that at least one of the first item or the first category of items is related to the second item; and transmitting, to the user, an explanation of a nature of at least one of the optional accessory relationship, the necessary accessory relationship, or the consumable accessory relationship assigned to the first item or the first category of items with respect to the second item.