You’re in a major American city and need to get somewhere. You don’t have a car, and public transportation won’t help, so you’re going to take a taxi — but why stand at the curb and try to hail a passing cab when you can use an app on your smartphone to request a ride from a non-professional driver in their own car? These alternate taxi services have become very popular over the last year. Why?

I talked it over with Geoffrey Fowler, personal technology columnist for the Wall Street Journal, who compared three of these services — Uber, Lyft, and Sidecar. We discussed the difference in cost, the safety issue, and the controversial “surge pricing” (in which prices can go way up at rush hour).

Listen, then click here to subscribe to these podcasts via iTunes!