11. The method of claim 8 , wherein the prior user interactions include a first prior user interaction and a second prior user interaction and wherein the first plurality of categories includes a first category and a second category.
11. The method of claim 8 , wherein the prior user interactions include a first prior user interaction and a second prior user interaction and wherein the first plurality of categories includes a first category and a second category. 13. The method of claim 11 , wherein the second prior user interaction includes viewing an item that is described by the second listing that is included in the second category.