13. The server of claim 12 , wherein the instructions cause the server to determine that the URI is not stored in a cache or database.
12. The server of claim 11 , wherein the instructions cause the server to: subsequent to detecting the user-initiated interaction with the web document and responsive to determining that a copy of the web document has not previously been analyzed to identify topics to which the web document relates, request and receive a copy of the web document from a content source identified by the URI and perform a textual analysis of the web document to identify the one or more topics to which the web document relates.