Uber, a San Francisco startup, allows riders to hail taxis via iPhones, text messages or the company's website. Users pay for cabs using a credit card that the company keeps on file. The app also makes it easier for taxi drivers to locate customers during off-peak hours, the company says.
Uber has been controversial, however, sparking opposition from regulators and taxi companies in several cities. Earlier this month, taxi companies in Chicago sued Uber, accusing the startup of violating laws meant to protect consumers and public safety.