In order to illustrate the importance and application of these conditions let us consider the example of a butcher. Instead of advertising his meat prices he may wait until the customer comes into the shop and charge prices according to an assessment of the individual customer’s ability and willingness to pay. Such a strategy may be successful in the case of customers who are ignorant of the prices being charged to other customers; however, once they become aware of this situation, and assuming that other butchers are following the same practice, high-paying consumers will find ways to avoid paying higher prices by buying their meat from other customers, in other words arbitrage will occur. Arbitrage refers to the practice of buying at a lower price and selling at a higher price to make a riskless profit. Thus in this instance a butcher cannot successfully practise price discrimination. On the other hand, a dentist is in a position to do so; patients cannot ask other patients to have their teeth capped for them. Thus price discrimination is generally easier in the markets for services, especially personal and professional services.