13. One or more non-transitory computer-readable media having computer executable instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising: determining that a user has interacted with a first item of a catalog of items; parsing explicit associative relationships between the first item and at least one type of related items from the catalog of items, the explicit associative relationships including words or phrases that define a relationship between the first item and the at least one type of related items, wherein the relationship is at least one of: an optional accessory relationship that indicates that the at least one type of related items are both suggested for use with the first item and not necessary for using the first item, a necessary accessory relationship that indicates that the at least one type of related items are necessary for using the first item, or a consumable accessory relationship that indicates that the at least one type of related items is consumed during use in conjunction with the first item; based at least partly on the parsing, identifying, in the other items, related items that are determined to be usable in conjunction with the first item; and presenting, to the user, one or more recommendations that identify at least some related items of the at least one type of related items, wherein the one or more recommendations include an explanation of a nature of the relationship.
19. The one or more non-transitory computer-readable media as recited in claim 13 , wherein the operations further comprise: determining that the user has interacted with the first item via a website or an application associated with a service provider; and dynamically presenting the one or more recommendations via the website or the application in response to determining that the user has interacted with the first item.