Airbnb facilitates the booking of over 37 million overnight stays per year. Uber operates in 450 cities in 60 countries. Both claim to be part of the rapidly growing `sharing economy' - but what does that actually mean? Here, Tom Slee offers a razor-sharp examination of the `sharing economy': from its genesis in open-source software and media file sharing, through to the present day popularity of Uber, Airbnb, Taskrabbit, and similar services, which operate outside of normal business regulations, taking on none of the risk or responsibility when something goes wrong. He asks, how did we get from the generosity of what's mine is yours, to the self-interest and greed of what's yours is mine?