Social costs refer to the total costs to society from the production or consumption of a good or service, encompassing both private costs incurred by producers and consumers, and external costs imposed on third parties not involved in the transaction. This concept highlights the disparity between private and social costs, which can lead to market failures when decisions are made solely based on private costs without considering the broader implications for society. Understanding social costs is essential for analyzing market outcomes and determining whether they are socially efficient or inefficient.