Markets work well with goods that economists call private goods.

Many markets work best with little or no outside interference. But others - especially those subject to big 'externalities' - need a helping hand.

How do we ensure in the case of public goods that they are provided at all, and that they are provided at the right level, taking into account citizens' preferences?

In various countries around the world, assets that had previously been in the hands of governments were sold off to the private sector in the hope that this would lead to a more efficient allocation, that these assets would be put to better use.

There are some things that we value as a public good that the markets can't deliver, like clean air.

What we mean by an outcome will naturally depend on the context. Thus, for a government charged with delivering public goods, an outcome will consist of the quantities provided of such goods as intercity highways, national defense and security, environmental protection, and public education together with the arrangements by which they are financed.