The trials of Uber

You need a ride. Instead of lingering at the intersection flailing your hand in the air, you fish out your smartphone. A few taps later, Uber's slick, futuristic logo appears, a seriffed "U" hovering over a stark black background. Signing up takes a few seconds. Once you provide basic contact and credit card information, a Google map pops up displaying your nearby surroundings. You select a spot on the screen to set a rendezvous and watch as a car-shaped icon inches toward it. When a black sedan pulls up a few minutes later, the driver welcomes you by name and offers free snacks and bottled water. At your destination, the fare is automatically charged to your card. No fumbling with wadded cash. No flimsy receipts to stash. You simply hop out and go.

In eight major cities, including New York, Paris, and Washington D.C., three-year-old startup Uber is trying to remake the cab experience. Drivers aren't employed by Uber, but get a cut of each fare instead. The arrangement can be lucrative, bringing in upwards of $500 a day, a sum some cab drivers only make after a week's work. Rates take into account the typical factors of time and distance but -- through an Uber-developed algorithm -- also factor in demand. Uber's servers crunch information about a where riders are requesting cars, where they're likely to want to go, even traffic-distorting big events nearby. When a Giants in San Francisco game lets out, several Uber cars are likely close-by. The man behind Uber is Travis Kalanick.