9. The method of claim 7 , wherein receiving information about the entity from the plurality of sources comprises receiving the information about the entity from a plurality of information feeds.
7. A method being performed by one or more computing devices including at least one processor, the method for maintaining a persistent entity index, the method comprising: receiving information about an entity from a plurality of sources, the received information including at least one attribute associated with the entity, the at least one attribute describing at least one characteristic of the entity; detecting a match between the information about the entity from at least two matching sources of the plurality of sources; aggregating the information about the entity from the at least two matching sources; storing the aggregated information in the persistent entity index, wherein the persistent entity index comprises a plurality of entity-attribute pairs from a first knowledge source and information acquired about entities from a second knowledge source; and incrementally updating the persistent entity index at a predetermined time interval to include updated entity-attribute pairs including any subsequently received attributes describing one or more characteristics of any entity of the persistent entity index.