Abstract: Methods, systems, and apparatus, including computer programs, for a social search engine. In one aspect, a method includes receiving an answer to a question from an answerer; identifying an entity in the answer, in which the entity refers to a product, a service, a company, or a merchant; obtaining permission from the answerer to provide an interactive link for the entity in the answer to a resource from which the entity can be obtained; receiving a user submitted query and determining that the query is related to the entity; and responsive to determining, providing the answer, including the link to the resource, as part of search results that are responsive to the query.

Abstract: Methods, systems, and apparatus, including computer programs, for a social search engine. In one aspect, a method includes receiving an answer to a question from an answerer; identifying an entity in the answer, in which the entity refers to a product, a service, a company, or a merchant; obtaining permission from the answerer to provide an interactive link for the entity in the answer to a resource from which the entity can be obtained; receiving a user submitted query and determining that the query is related to the entity; and responsive to determining, providing the answer, including the link to the resource, as part of search results that are responsive to the query.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for selecting users that are connected to a particular user; accessing, for each of the selected users, an interest score of the selected user that reflects the selected user's predicted interest in the particular topic, or interest data that that is used to determine the interest score of the selected user; accessing a model that is used for generating the interest score of the particular user that reflects the particular user's predicted interest in the particular topic, wherein the interest score of the particular user is generated based at least on the interest scores or interest data of the selected users for the particular topic; and applying the interest scores or interest data of the selected users for the particular topic to the model to generate the interest score of the particular user for the particular topic.