1. A method, comprising: extracting, by one or more processors of one or more computing devices, a keyword candidate from a document, of a plurality of documents, where each of the plurality of documents is mapped to at least one of a plurality of categories, and where the keyword candidate is included in the document and within one or more prior search queries; calculating, by the one or more processors, a respective frequency that the keyword candidate appears in each of the plurality of categories, where the frequency that the keyword candidate appears in a particular one of the plurality of categories corresponds to a number of occurrences of the keyword candidate in a subset, of the documents, mapped to the particular one of the categories; associating, by the one or more processors and as a keyword, the keyword candidate with the document in response to: determining that each of the respective calculated frequencies, associated with at least one category, of the plurality of categories, to which the document is mapped, exceeds a threshold, and determining that each of the respective calculated frequencies, associated with other categories, of the plurality of categories, to which the document is not mapped, do not exceed the threshold; and prioritizing, by the one or more processors, the document in search results produced in response to a search query related to the keyword and the at least one category associated with the document, where the search query is received after the one or more prior search queries.
1. A method, comprising: extracting, by one or more processors of one or more computing devices, a keyword candidate from a document, of a plurality of documents, where each of the plurality of documents is mapped to at least one of a plurality of categories, and where the keyword candidate is included in the document and within one or more prior search queries; calculating, by the one or more processors, a respective frequency that the keyword candidate appears in each of the plurality of categories, where the frequency that the keyword candidate appears in a particular one of the plurality of categories corresponds to a number of occurrences of the keyword candidate in a subset, of the documents, mapped to the particular one of the categories; associating, by the one or more processors and as a keyword, the keyword candidate with the document in response to: determining that each of the respective calculated frequencies, associated with at least one category, of the plurality of categories, to which the document is mapped, exceeds a threshold, and determining that each of the respective calculated frequencies, associated with other categories, of the plurality of categories, to which the document is not mapped, do not exceed the threshold; and prioritizing, by the one or more processors, the document in search results produced in response to a search query related to the keyword and the at least one category associated with the document, where the search query is received after the one or more prior search queries. 2. The method of claim 1 , where the extracting the keyword candidate comprises: analyzing user behavior data associated with search results associated with the one or more prior search queries; and extracting the keyword candidate based on analyzing the user behavior data.