Forwarding you to

Microsoft open sources algorithm that gives Bing some of its smarts | Ars Technica

Search engines today are more than just the dumb keyword matchers they used to be. You can ask a questionsay, "How tall is the tower in Paris?"and they'll tell you that the Eiffel Tower is 324 meters (1,063 feet) tall, about the same as an 81-story building. They can do this even though the question never actually names the tower.