Final answer:
A deadweight loss occurs when price is artificially kept above or below equilibrium, leading to an inefficient market outcome and a reduction in society's total surplus.
Step-by-step explanation:
A deadweight loss occurs when there is a loss in social surplus due to the economy producing at an inefficient quantity. This usually happens when a price control is in place, either as a price ceiling (price kept below equilibrium) or price floor (price kept above equilibrium). Therefore, a deadweight loss occurs when price is artificially kept above or below equilibrium, which leads to a reduction in the total surplus of society and blocks potential transactions between suppliers and demanders that would have been beneficial for both parties.