16. A method comprising: providing, using one or more processors, a desirability index including a plurality of desirability values, the desirability index being built such that each desirability value is associated with a keyword, is determined according to a numerical value assigned to a selected item listing having the keyword based upon a sale format associated with the selected item listing, and indicates an accumulative frequency of the keyword being included in a first set of one or more item listings selected throughout a number of user transactions, the assigning of the numerical value comprising determining the numerical value based at least in part on whether the sale format associated with the selected item listing is a fixed price sale or a non-fixed price sale; identifying, using the one or more processors, a search result including a second set of one or more item listings in response to a query from a user device, each item listing including a plurality of keywords; accessing, using the one or more processors, for each item listing, the desirability index and obtaining a desirability value for each keyword included in the item listing; calculating, using the one or more processors, a relevancy value for each item listing, the relevancy value being an accumulation of the desirability values for the keywords included in the item listing; and sorting, using the one or more processors, the item listings in the search result according to the relevancy values for the item listings and returning the sorted item listings to the user device.
16. A method comprising: providing, using one or more processors, a desirability index including a plurality of desirability values, the desirability index being built such that each desirability value is associated with a keyword, is determined according to a numerical value assigned to a selected item listing having the keyword based upon a sale format associated with the selected item listing, and indicates an accumulative frequency of the keyword being included in a first set of one or more item listings selected throughout a number of user transactions, the assigning of the numerical value comprising determining the numerical value based at least in part on whether the sale format associated with the selected item listing is a fixed price sale or a non-fixed price sale; identifying, using the one or more processors, a search result including a second set of one or more item listings in response to a query from a user device, each item listing including a plurality of keywords; accessing, using the one or more processors, for each item listing, the desirability index and obtaining a desirability value for each keyword included in the item listing; calculating, using the one or more processors, a relevancy value for each item listing, the relevancy value being an accumulation of the desirability values for the keywords included in the item listing; and sorting, using the one or more processors, the item listings in the search result according to the relevancy values for the item listings and returning the sorted item listings to the user device. 18. The method of claim 16 , wherein the desirability values for the keywords are not accumulated to calculate the relevancy value upon determination of the desirability values being modified prior to a specified temporal range.