From AirBnB and Uber to tool libraries and swapping fairs, we’re now selling, bartering, and sharing things with each other on an unprecedented scale, thanks to new technologies. Anne Wright-Howard examines how this new economic model challenges 20th century notions of ownership, commerce, government regulation, wealth and personal identity. Tonya Surman is featured, along with Rachel Botsman, Jeremiah Owyang, Nathan Blecharczyk and others.