Answer:
It is an illegal market that emerges when only binding price ceilings and binding price floors are in place.
Explanation:
A black market can be defined as an illegal market that emerges as a result of binding price ceilings and price floors.
A binding price ceiling fixes the price below the equilibrium market price. This creates a shortage in the market as the quantity demanded is greater than quantity supplied. This causes a black market to emerge where the price is above ceiling limit.
Similarly, a binding price floor fixes price above the equilibrium level. This creates a surplus in the market where the quantity supplied is greater than quantity demanded. So a black market emerges where the price is lower than the floor limit.