Google, as a search engine, had built a fine business by “indexing” all of these documents and making them searchable. The company was built on a principle of centralization: If you take the chaotic Web and bestow order upon it, merge it into a single consolidated index, make it make sense, you can make users very, very happy. And upon that index, and that shared happiness, and the willingness of some users to click on targeted advertising, Google could construct a tremendous enterprise. An empire, if you will. Except empires are not traditionally constructed from indexing documents. But maps are.