...As the overwhelming search leader, Google has advantages that tend to reinforce one another. It has the most people typing in searches — billions a day — and that generates more data for Google’s algorithms to mine to improve its search results. All those users attract advertisers. And there is the huge behavioral advantage: “Google” is synonymous with search, the habitual choice.Once it starts, this cycle of prosperity snowballs — more users, more data, and more ad dollars. Economists call the phenomenon “network effects”; business executives just call it momentum. In search, Google has it in spades, and Microsoft, against the odds, wants to reverse it.