Second degree price discrimination is where a firm sells at different prices based on quantity. This may include offers such as buy two, get one free, or 20 percent off when you buy six.
An explicit cost is the clearly stated costs that a business incurs. For example, employee wages, inputs, utility bills, and rent, among others. These are the costs which are stated on the businesses balance sheet.
By contrast, implicit costs are those which occur, but are not seen. In other words, these are the costs that are not directly linked to an expenditure. For example, a factory may close down for the day in order for its machines to be serviced.