Theoretically, a free market
is an economy
which is only regulated
by "market forces", i.e. Supply and Demand
between businesses is expected to self-regulate
within a free market.
In reality, however, totally free markets breed an incredibly destructive "race to the bottom" in which all involved attempt to amass the most capital and resources at the expense of everyone else.
Modern neoliberal capitalists extoll the virtues of free markets while conveniently ignoring the fact that no such thing exists. All "free markets" today are propped up with massive government subsidies such as corporate welfare and radical tax-relief for the wealthy. This is simply because a true free market will eventually collapse under the weight of the boundless greed of those involved.
While the poor, lower-middle and middle classes are subjected to the market discipline of Supply and Demand, the upper classes are eternally given a helping hand by that wonderful guardian of power and priviledge, the State. It is entirely common and expected that the costs of big business will be socialized (via tax subsidies, land grants, EPA cleanup of environmental damage, etc.) while all profits are privatized.