7. A non-transitory computer-readable storage medium encoded with a computer program, the computer program comprising instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising: providing a user interface that includes first control through which a user may enter one or more query terms of a search query, and a second control through which the user may activate a search mode that selects search results for presentation without regard to at least one of geographic data, language data, user search history data, or social network information related to the user and that, when a search session ends, automatically reverts to a default search mode that selects search results for presentation using at least one of geographic data, language data, user search history data, or social network information related to the user; receiving (i) the search query, and (ii) data indicating that a user that submitted the search query has selected the second control to activate the search mode that selects search results for presentation without regard to at least one of geographic data, language data, user search history data, or social network information related to the user and that, when the search session ends, automatically reverts to the default search mode that selects search results for presentation using at least one of geographic data, language data, user search history data, or social network information related to the user; based on receiving the data indicating that the user that submitted the search query has activated the search mode, selecting particular search results for presentation in response to the search query, without regard to at least one of geographic data, language data, user search history data, or social network information related to the user; determining that a search session that included the received search query has ended; and in response to determining that the search session that included the received search query has ended, automatically reverting to a default search mode that selects search results for presentation using at least one of geographic data, language data, user search history data, or social network information related to the user.
7. A non-transitory computer-readable storage medium encoded with a computer program, the computer program comprising instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising: providing a user interface that includes first control through which a user may enter one or more query terms of a search query, and a second control through which the user may activate a search mode that selects search results for presentation without regard to at least one of geographic data, language data, user search history data, or social network information related to the user and that, when a search session ends, automatically reverts to a default search mode that selects search results for presentation using at least one of geographic data, language data, user search history data, or social network information related to the user; receiving (i) the search query, and (ii) data indicating that a user that submitted the search query has selected the second control to activate the search mode that selects search results for presentation without regard to at least one of geographic data, language data, user search history data, or social network information related to the user and that, when the search session ends, automatically reverts to the default search mode that selects search results for presentation using at least one of geographic data, language data, user search history data, or social network information related to the user; based on receiving the data indicating that the user that submitted the search query has activated the search mode, selecting particular search results for presentation in response to the search query, without regard to at least one of geographic data, language data, user search history data, or social network information related to the user; determining that a search session that included the received search query has ended; and in response to determining that the search session that included the received search query has ended, automatically reverting to a default search mode that selects search results for presentation using at least one of geographic data, language data, user search history data, or social network information related to the user. 10. The non-transitory computer-readable storage medium of claim 7 , wherein the social network information related to the user includes a plurality of social graphs associated with the user, and wherein different types of the social graphs are generated for different connections of the users.