When someone performs a search at one of the major search engines, the search engine focuses upon returning as quick and helpful an answer as possible. Part of that can involve looking the query up in a “trending topics” database to see if there’s some recent news that should be reported to the searcher. This is how the search engines are increasingly becoming a real time monitor of world events.
A recently granted patent at Yahoo (Bing has taken over crawling of web pages for Yahoo, but the deal between the two companies allows Yahoo to massage the data they receive and show off the results they want to) describes how they might “identify… and recommend… queries related to trending topics based on a query received from a user of an information retrieval system.”
The patent describes its focus and the challenges it intends to overcome as follows: