Demonstrators in San Francisco have been protesting outside apartment buildings that have units rented through online brokers. Justin Sullivan/Getty Images hide caption

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Taxi drivers protest against Uber, an on-demand car service app, during a 24-hour strike July 1 in Barcelona, Spain. They say it undercuts their business and are calling for the government to ban it. David Ramos/Getty Images hide caption

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Airbnb, the online home-rental service, says it will start collecting hotel taxes in a few American cities. Chris Weeks/Getty Images hide caption

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A search for places to stay in New York City via Airbnb returns plenty of results, despite the practice of short-term rentals being found to be illegal under city and state law. Airbnb hide caption

itoggle caption Airbnb