What are the concequences of implimenting minumum or maximum prices for goods and services?

When a maximum price is set for a good or service, it is set below the equilibrium. This is supposed to help consumers but due to the excess demand, a black market will emerge and goods and services will be sold at black market prices (which will be higher than the maximum price or price ceiling) A minumum price is set abouve the equlibrium price. This is done to help producers, however all this will do is create an excess supply and a black market will emerge where goods will be sold at a lower price.