2. A method as in claim 1 , wherein each address of the list of addresses includes metadata indicating a time at which the user visited the website to which the address corresponds; wherein acquiring the web browsing history includes: for each address of the list of addresses of the web browsing history: selecting the address when the metadata indicates that the user visited the website to which the address corresponds later than a threshold time, and not selecting the address when the metadata indicates that the user visited the website to which the address corresponds earlier than the threshold time.
2. A method as in claim 1 , wherein each address of the list of addresses includes metadata indicating a time at which the user visited the website to which the address corresponds; wherein acquiring the web browsing history includes: for each address of the list of addresses of the web browsing history: selecting the address when the metadata indicates that the user visited the website to which the address corresponds later than a threshold time, and not selecting the address when the metadata indicates that the user visited the website to which the address corresponds earlier than the threshold time. 3. A method as in claim 2 , wherein the metadata further indicates a set of keywords used to make a search engine aware of the website when keywords of the set of keywords are entered into the search engine; wherein acquiring the web browsing history further includes: inputting a keyword of the set of keywords into the search engine; after inputting the keyword into the search engine, obtaining addresses of an alternate website that was listed as output of the search engine; wherein deriving the external facts includes: deriving facts from the alternate website.