1. A method comprising: collecting query data, the query data indicating a query term and tracked user behavior associated with past queries involving the query term; calculating, using the collected query data, an aspect demand ratio for each category of a category tree that comprises listings of items, the category tree comprising a hierarchy of categories organized into a plurality of levels, the aspect demand ratio calculated based on an aspect demand total count for a category divided by a total count of a highest level category in the hierarchy of the category tree, the calculating performed by a hardware processor; using the aspect demand ratio for each category to determine one or more lowest level categories in the hierarchy of the category tree that satisfies a category threshold; appending the one or more lowest level categories in the hierarchy of the category tree and a top number of aspect name/value pairs of the items in the listings within the one or more lowest level categories in the hierarchy of the category tree to the query term in a database; receiving, via a user interface, a new query; performing a lookup in the database using a query term of the new query to determine the one or more lowest level categories in the hierarchy of the category tree and the top number of aspect name/value pairs of the items in the listings within the one or more lowest level categories in the hierarchy of the category tree corresponding to the query term of the new query; and causing presentation, in a category and aspect portion of the user interface, of the one or more lowest level categories and the top number of aspect name/value pairs of the items in the listings within the one or more lowest level categories, each entry in the category and aspect portion being selectable to narrow down on a category of interest.