A price ceiling is the maximum amount a producer can sell their good or service for. This is usually mandated by government in order to ensure consumers can afford the relevant goods and services. Examples include, food, rent, and energy products which may become unaffordable to consumers.
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.