Anna Morgenstern has a recent piece up at the Center for a Stateless Society talking about what distinguishes a market as "free."  She writes:

Libertarians throw the phrase “free market” around a lot, but the important word among those two is free.  Markets, per se, are really an after-thought. It’s not as if we don’t want freedom in our non-market activities.  We want to have freedom, in all ways, including in our “market transactions”.  The word market confuses a lot of people because they imagine “markets” to be an institution, a thing that one can point to and say “this is a Market”.  But we don’t mean it that way, really.  There’s no such thing as a market.  It’s just a catch-all term to cover the sum total of all exchanges.

The only alternative to a market is to have rationing by command.  One monopoly with control of all goods who hands them out to people according to a scheme that monopoly has planned out in advance.  A situation where there is any sort of trade at all, is technically a market.

Read the rest here.